The A1c tells you where your average has been. A continuous glucose monitor tells you where you're going — and what's driving the swings. The difference between managing diabetes by average and managing it by pattern is the difference between knowing your monthly bank balance and seeing every transaction. Both matter, but one gives you far more to work with.
What A1c Misses — and Why It Matters
We covered A1c in depth in Post 4 — Complications and Targets. The short version: A1c reflects average blood glucose over approximately three months, but two people can have identical A1c values while living in completely different glucose realities. One person might have stable, consistent glucose throughout the day. Another might be oscillating between dangerous lows and dangerous highs, with the highs and lows averaging out to the same number. The first person is doing well. The second is at elevated risk for hypoglycemic emergencies, the oxidative damage caused by glucose spikes, and the anxiety and impaired quality of life that come with an unpredictable glucose profile.
This is the problem that continuous glucose monitoring (CGM) was designed to solve. Rather than a single number every three months, CGM provides a glucose reading every few minutes — showing trends, peaks, valleys, and patterns over days and weeks. The key metric that has emerged from CGM data is time-in-range: the percentage of time glucose stays within a target window, typically 70–180 mg/dL. Time-in-range correlates with complication risk in ways that A1c alone cannot capture.
CGM: What It Is and How It Works
A CGM consists of a small sensor inserted just under the skin — typically on the upper arm or abdomen — that measures glucose in the fluid surrounding cells (interstitial fluid) every 1–5 minutes. This glucose measurement correlates closely with blood glucose but lags behind by approximately 5–15 minutes, which matters when glucose is changing rapidly. The sensor transmits readings wirelessly to a smartphone or receiver, and most systems display the current glucose level, the rate and direction of change (a falling arrow means glucose is dropping, a rising arrow means it is rising), and a graph of the last few hours.
There are two main types. Real-time CGM (rtCGM) continuously displays the reading and alerts the user when glucose goes out of range — this is the current standard and what most new devices use. Intermittently scanned CGM (isCGM, such as the original FreeStyle Libre) is an older format that requires the user to actively scan the sensor with a reader or phone to get a reading, and does not alert automatically unless glucose goes critically low. isCGM is largely being replaced by real-time systems as the technology matures, but it remains available and is a reasonable choice for patients who prefer a dedicated reader over a smartphone, or who simply want trend data without active alerts. For patients who experience hypoglycemia unawareness or need active low-glucose alerts, rtCGM is strongly preferred.
CGM in Type 2 diabetes
CGM is now standard of care for Type 1 diabetes and is increasingly used and supported in Type 2. The evidence in insulin-treated Type 2 shows A1c reductions of approximately −0.35–0.45% and consistent improvements in time-in-range. A large Veterans Affairs study found that initiating CGM in insulin-treated Type 2 patients was associated with a 13% reduction in hyperglycemia-related events and a 25% reduction in all-cause hospitalization. Even in non-insulin-treated Type 2, RCT data now show meaningful A1c and time-in-range improvements — partly from the behavioral feedback CGM provides, helping patients understand in real time how specific foods, meals, and activities affect their glucose.
Time-in-Range: The Metric That Changes Management
Time-in-range (TIR) — the percentage of time glucose stays between 70 and 180 mg/dL — has become the primary CGM-derived outcome in clinical trials and increasingly in clinical practice. Higher TIR is associated with lower rates of retinopathy, albuminuria, cardiovascular mortality, and all-cause mortality. Peripheral neuropathy correlates most strongly with glucose variability metrics (how much glucose swings around), reinforcing that controlling the swings matters as much as controlling the average.
The international consensus targets, endorsed by the ADA, are shown below. These are not arbitrary thresholds — they were chosen to approximate an A1c of approximately 7% when achieved, while providing additional information about hypoglycemia and variability that A1c cannot.
CGM Targets — International Consensus (ADA 2026)
Metric
Most Adults
Older / High-Risk
What It Means
Time in range (70–180 mg/dL)
>70%
>50%
The primary goal. >70% approximates an A1c of ~7%. Each 10% increase in TIR corresponds to roughly 0.5% A1c reduction.
Time below 70 mg/dL (low)
<4%
<1%
Level 1 hypoglycemia — symptomatic low. Goal is to minimize this entirely in older and frail patients.
Time below 54 mg/dL (very low)
<1%
<1%
Level 2 hypoglycemia — clinically significant, dangerous. Less than 15 minutes per day at this level is the target.
Time above 180 mg/dL (high)
<25%
<50%
Level 1 hyperglycemia. Less than 6 hours per day above 180 in most adults.
Time above 250 mg/dL (very high)
<5%
<10%
Level 2 hyperglycemia — significant complication risk. Less than ~70 minutes per day above this threshold.
Coefficient of variation (CV)
≤36%
≤36%
Measures glucose variability — how much glucose swings around the average. CV above 36% predicts higher hypoglycemia risk and correlates with neuropathy progression.
My Synthesis
The coefficient of variation is the metric I find most useful for identifying patients whose glucose is technically "controlled" by A1c but who are actually living with dangerous instability. A patient with A1c 7.2% and CV of 45% is not well-controlled — they are oscillating widely, spending time in significant lows and highs that are averaging to an acceptable number. My approach is to address variability first: stabilize the swings before pushing aggressively toward a lower average. A stable A1c of 7.5% is clinically safer than a volatile A1c of 6.9%.
Fingerstick Glucose Monitoring: When It's Actually Needed
Traditional fingerstick blood glucose monitoring — pricking a finger and placing a drop of blood on a test strip — remains useful in specific situations. CGM measures glucose in the fluid between cells, not directly in blood, and lags behind blood glucose by 5–15 minutes when glucose is changing rapidly. During steep post-meal rises, rapid hypoglycemia correction, or exercise, CGM readings can be meaningfully inaccurate. Most manufacturers recommend confirming with a fingerstick before treating hypoglycemia if symptoms don't match the CGM reading.
In my practice, I don't routinely recommend fingerstick monitoring for patients who are not on insulin or hypoglycemia-causing medications (sulfonylureas). For those patients, routine fingerstick testing rarely changes management and adds burden without proportional benefit. The exception is patients who want to use real-time glucose data to understand how specific foods or meals affect them — in that context, even occasional targeted checking can be genuinely informative and help build intuition about dietary choices.
For patients on insulin who cannot access CGM due to cost or preference, structured fingerstick monitoring — before meals, two hours after meals, at bedtime, and whenever symptoms occur — still provides the actionable pattern data needed to adjust doses safely. CGM is strongly preferred for all insulin-treated patients, but fingerstick monitoring remains a viable and practical option when CGM is not accessible.
Insulin Types and What They Do
For patients requiring insulin — all Type 1, and many Type 2 — understanding the different insulin types is essential for managing glucose effectively. Modern insulin therapy aims to mimic the normal pattern of insulin secretion: a steady background level (basal) supplemented by meal-related doses (bolus). Different insulin preparations achieve different parts of this profile.
The chart below shows the approximate action profiles of the main insulin types — when each starts working, when it peaks, and how long it lasts. These are averages; individual response varies.
Insulin Action Profiles — Onset, Peak, and Duration
Profiles are approximate averages — individual response varies with injection site, dose, temperature, and metabolic factors.
Basal insulin provides a steady, low-level background of insulin over 12–24+ hours, suppressing the liver's glucose output between meals and overnight. It does not cover meals — it is the foundation that keeps glucose stable when you're not eating. In Type 1 diabetes, the basal component typically accounts for 40–50% of total daily insulin. In Type 2, basal insulin alone is often the starting point before adding mealtime coverage if needed.
The clinically meaningful difference within this class is hypoglycemia risk, not glucose lowering. All long-acting insulins produce equivalent A1c reductions — the trials consistently show no meaningful A1c difference between agents. What differs is the stability and safety of the action profile. Second-generation agents — degludec (Tresiba) and glargine U-300 (Toujeo) — have longer, flatter, near-peakless profiles. The DEVOTE trial showed degludec reduced severe hypoglycemia by 40% and nocturnal severe hypoglycemia by 53% compared to glargine U-100, with identical A1c outcomes. For patients experiencing recurrent or nocturnal hypoglycemia on first-generation basal insulin, upgrading to a second-generation agent is evidence-based and clinically meaningful. For stable patients without hypoglycemia concerns, the less expensive first-generation agents are entirely appropriate.
NPH insulin — an older intermediate-acting human insulin — is substantially less expensive and remains a viable option in Type 2 diabetes for cost-constrained patients who are not experiencing significant nocturnal hypoglycemia. It requires twice-daily dosing and has a more pronounced peak than the long-acting analogs, making it somewhat less convenient and slightly higher-risk for overnight lows, but large real-world studies have not found dramatic differences in hypoglycemia-related hospitalizations when used in standard Type 2 management.
Rapid-acting insulin is taken at meals to cover the glucose rise from carbohydrate absorption. It begins working within 15–30 minutes, peaks at 60–90 minutes, and lasts approximately 3–5 hours. The dose is calculated based on how many carbohydrates are being eaten (insulin-to-carbohydrate ratio, or ICR) and whether a correction is needed for a high pre-meal glucose (using the insulin sensitivity factor, or ISF).
Within this class, lispro, aspart, and glulisine are clinically interchangeable. Meta-analysis of head-to-head trials finds no meaningful difference in A1c, hypoglycemia rates, or weight between them — choose based on cost and availability. The ultra-rapid formulations (Fiasp, Lyumjev) offer a modestly faster onset and a ~20 mg/dL improvement in 1-hour post-meal glucose compared to standard rapid-acting insulins, but produce no meaningful A1c difference (−0.02% in meta-analysis). They are a reasonable choice for patients with significant post-meal glucose spikes or those using closed-loop AID systems, but do not justify cost-driven switching if standard agents are working well. Timing matters: standard rapid-acting insulin is typically taken 15–20 minutes before a meal; ultra-rapid formulations can be taken at the start of or even during a meal.
Regular human insulin (available over the counter at Walmart as ReliOn, ~$25/vial without prescription) has a slower onset (30–60 min) and longer duration (6–8 hours) than rapid-acting analogs, making meal timing more challenging and late post-meal hypoglycemia more common. It is a legitimate option when cost is the primary barrier, but it requires taking the dose 30–45 minutes before eating — a practical challenge for many patients.
Biosimilar insulins are therapeutically equivalent to their brand-name reference products. Meta-analysis of 25 RCTs (10,617 patients) shows a mean A1c difference of 0.01% — effectively zero. A 1:1 switch from brand to biosimilar is appropriate and strongly supported by evidence. Select based on cost.
Correction Doses
Using rapid-acting insulin to bring elevated glucose back to target
Correction
A correction dose uses rapid-acting insulin to lower glucose that is above target, independent of a meal. The calculation uses the insulin sensitivity factor (ISF) — how many mg/dL one unit of insulin typically lowers blood glucose for that individual. For example, if an ISF is 50 mg/dL per unit, and glucose is 250 mg/dL with a target of 100 mg/dL, the correction dose would be (250 − 100) ÷ 50 = 3 units.
A critical principle: give correction doses time to work before giving another. Rapid-acting insulin takes 15–30 minutes to begin acting and peaks at 60–90 minutes. In practice, I recommend waiting at least 1–1.5 hours before reassessing whether a further correction is needed. Taking repeated corrections before the first has fully acted — called insulin stacking — is one of the most common causes of severe hypoglycemia in insulin-managed patients. CGM trend arrows are useful here: a flat or falling arrow means the correction is working; don't add more.
In my practice, I don't generally recommend manual correction doses for patients on multiple daily injections (MDI) unless they are detail-oriented and comfortable with the calculations involved — the margin for error is meaningful, and CGM and pump-based AID systems automate this far more safely. For appropriate patients who want this level of control, it is a legitimate tool, but it requires clear understanding of active insulin on board before each correction.
Delivers rapid-acting insulin continuously via a small under-skin catheter
Pump
An insulin pump replaces the need for long-acting insulin by delivering small, continuous doses of rapid-acting insulin throughout the day and night (the basal rate), with larger user-triggered doses at meals (boluses). Pumps allow basal rates to be programmed differently at different times of day — accounting for the dawn phenomenon (early-morning glucose rise driven by cortisol and growth hormone) and exercise periods, which multiple daily injections cannot achieve as precisely.
The major advance over the past decade is the automated insulin delivery (AID) system — sometimes called a closed-loop or artificial pancreas system — which connects the pump to a CGM and adjusts insulin delivery automatically based on glucose trends. These systems have produced the largest improvements in time-in-range of any diabetes technology to date.
Insulin Affordability: What Patients Should Know
Insulin cost is a genuine barrier to care for many patients, and the landscape of affordability programs has changed significantly in recent years. Every major insulin manufacturer now offers programs that cap monthly costs at $35 for eligible patients, and several pathways exist depending on insurance status.
⚠ Cost Should Not Be a Reason to Ration Insulin
Insulin rationing — taking less insulin than prescribed to make a supply last longer — is dangerous and contributes to DKA hospitalizations and deaths. If cost is a barrier, talk to your physician or pharmacist before reducing doses. Multiple programs exist to help.
📊 $35/Month Insulin Programs — Current Options
Long-acting (basal) insulin: Sanofi's Valyou Savings Program caps Lantus (glargine U-100) and Toujeo (glargine U-300) at $35/month for up to 10 packs per fill for uninsured or commercially insured patients paying cash. Generic glargine (Basaglar, biosimilar) is often available for $35 or less at major pharmacies with GoodRx or similar discount cards.
Rapid-acting insulin — Eli Lilly (Humalog, Insulin Lispro): Lilly Insulin Value Program — $35/month for up to a 30-day supply. Available at participating pharmacies for commercially insured or uninsured patients. Visit InsulinAffordability.com or call 833-808-1234.
Rapid-acting — Novo Nordisk (NovoLog, Fiasp): My$99Insulin or Copay Savings Card — as low as $25–35/month for up to 3 vials or 2 packs of pens. Commercially insured or uninsured. Visit NovoCare.com or text SAVE to 97430.
Rapid-acting — Sanofi (Apidra, Admelog): Valyou Savings Program — $35/month for uninsured patients or commercially insured patients paying cash. Visit TeamingUpForDiabetes.com or call 800-633-1610.
Medicare patients: The Inflation Reduction Act caps insulin costs at $35/month for Medicare Part D beneficiaries for all covered insulins — no manufacturer program needed.
Over-the-counter option: ReliOn regular human insulin at Walmart costs approximately $25/vial without a prescription. This is regular (not rapid-acting analog) insulin with a different action profile requiring adjusted meal timing, but it is a viable option when other programs are inaccessible. Discuss the timing differences with your physician before switching.
CGM Affordability: Options for Every Budget
Prescription CGM devices — Dexcom G7, FreeStyle Libre 3, and similar — are covered by most insurance plans and Medicare for patients on insulin or with a qualifying diagnosis. For patients without insurance or with high out-of-pocket costs, the price can be prohibitive. Several programs now exist to significantly reduce or eliminate that cost.
📊 CGM Cost Reduction Programs
Dexcom Patient Assistance Program (PAP) — for uninsured Type 1 patients: Dexcom offers a formal patient assistance program for qualifying patients with Type 1 diabetes who lack insurance coverage. Provides CGM supplies at no or reduced cost. Apply at assistance.dexcom.com. Unlike the copay card, the PAP has income and eligibility requirements but covers the full cost for those who qualify.
Dexcom Copay Card — for insured and cash-pay patients: Available to commercially insured patients and cash-pay patients without the same income restrictions as the PAP. Reduces out-of-pocket cost significantly. Details at dexcom.com/savings-center. Worth asking your physician's office about regardless of insurance status.
FreeStyle Libre Copay Savings Card (Abbott): Abbott offers a copay savings card for the FreeStyle Libre 2 and Libre 3 that reduces patient cost for commercially insured patients. Available at freestyle.abbott/us-en/private-insurance.html — does not have the same eligibility restrictions as formal patient assistance programs. Patients can apply directly online.
Medtronic: Medtronic's CGM (used in its integrated pump systems) does not have a standalone CGM assistance program comparable to Dexcom or Abbott. Medtronic's patient assistance is primarily available for patients using its insulin pump systems. Patients interested in Medtronic CGM who face cost barriers should ask their physician about pump-inclusive programs or consider whether a standalone CGM brand is more accessible.
⚠ OTC CGMs Have Lower Glucose Upper Limits — Important for Diabetes Management
Over-the-counter CGMs (Stelo, Lingo) typically have an upper measurement limit of approximately 250 mg/dL — above that level, they display a "HIGH" reading without a specific number. Prescription clinical CGMs (Dexcom G7, FreeStyle Libre 3) measure up to approximately 400 mg/dL and display the actual value. For patients with diabetes who may experience glucose values above 250 — particularly during illness, after a missed dose, or in poorly controlled Type 2 — this is a meaningful limitation. If your glucose reads "HIGH" on an OTC device, you don't know whether it's 260 or 380, which matters significantly for how aggressively to act. This is one additional reason OTC devices are appropriate as a starting tool for non-insulin-treated Type 2 patients with reasonably controlled glucose, but not as a substitute for clinical-grade CGM in higher-risk situations.
📊 OTC vs. Prescription CGM — Key Differences
Stelo (Dexcom, OTC) and Lingo (Abbott, OTC): Available without a prescription at major pharmacies. Approximately $89/month (two 15-day sensors for Stelo). Provides real-time glucose readings on a smartphone app with trend data. No hypoglycemia alerts. Upper glucose limit ~250 mg/dL. Slightly slower response time than clinical devices. Not suitable for insulin management.
Prescription CGM (Dexcom G7, FreeStyle Libre 3): Requires prescription. Covered by most insurance and Medicare for eligible patients. Real-time alerts for low and high glucose. Upper limit ~400 mg/dL. Faster sensor response. Integration with automated insulin delivery systems. Standard of care for insulin-treated patients.
My recommendation: For uninsured non-insulin-treated Type 2 patients with reasonably controlled glucose, Stelo or Lingo is substantially better than no monitoring and provides meaningful dietary and lifestyle feedback at a fraction of the cost of prescription devices. For insulin-treated patients and those with higher glucose variability, explore the assistance programs above before settling for an OTC device — the safety gap from missing hypoglycemia alerts and the upper-limit restriction are real clinical concerns.
Automated Insulin Delivery: The Biggest Advance in Type 1 Management
Automated insulin delivery (AID) systems — which pair a CGM sensor with an insulin pump and an algorithm that adjusts insulin delivery in real time — represent the most significant advance in Type 1 diabetes management since CGM itself. They work by mimicking what a functioning pancreas does: sensing glucose levels every few minutes and adjusting insulin delivery accordingly, increasing basal delivery when glucose rises and suspending or reducing it when glucose is falling toward a low.
The clinical results are striking. The Control-IQ system (6-month randomized trial, New England Journal of Medicine) increased time-in-range from 61% to 71% — a gain of 10 percentage points, equivalent to more than 2 additional hours per day within target. Time below 70 mg/dL (hypoglycemia) was reduced simultaneously. The MiniMed 780G system showed similar results: TIR 70.4% versus 57.9% with standard pump therapy, a gain of 12.5 percentage points. Meta-analysis of AID systems shows consistent TIR improvements of 8–11 percentage points compared to standard pump therapy, with simultaneous reductions in both hyperglycemia and hypoglycemia time.
📊 Automated Insulin Delivery — Key Trial Results
Control-IQ (NEJM 2019, 6-month RCT): TIR increased from 61% to 71% (+10 percentage points). Time below 70 mg/dL simultaneously reduced. Both hyperglycemia and hypoglycemia improved — the hallmark of AID over manual management where reducing one often worsens the other.
MiniMed 780G (advanced hybrid closed-loop): TIR 70.4% vs. 57.9% with sensor-augmented pump (+12.5 percentage points). Significant reductions in both time above and time below range.
Children and young adults: Young children (2–6 years) gained approximately 3 hours per day in range with closed-loop versus standard care. A large pediatric meta-analysis showed 40–60% of youth using AID systems achieve recommended TIR targets, versus far fewer on conventional therapy.
Meta-analysis of free-living AID trials (2026): TIR improvement +8.8–11% versus sensor-augmented pump. A1c reduction −0.4% in pediatric populations. Simultaneous improvement in both hypoglycemia and hyperglycemia time — a combination that manual dose adjustment rarely achieves.
My Synthesis
For patients with Type 1 diabetes who are candidates for pump therapy, an AID system is now my strong recommendation over conventional pump or multiple daily injection therapy — not because it's newer, but because the outcome data are substantially better. The ability to automatically reduce insulin when glucose is falling prevents the nocturnal hypoglycemia that is one of the most dangerous and feared aspects of Type 1 management. The reduction in cognitive burden — not having to manually calculate and adjust every basal rate — is also real and meaningful for quality of life. The technology is not perfect, and it requires engagement and calibration, but the evidence is clear enough that I believe every appropriate patient should at minimum have a conversation about it.
Insulin Sequencing: Basal First, Then Bolus
For patients beginning insulin therapy — or struggling with poorly controlled glucose on their current regimen — the sequencing of adjustments matters. The principle, supported by ADA and EASD consensus, is basal first: establish stable overnight and fasting glucose before attempting to optimize mealtime doses.
The logic is straightforward. If background insulin is insufficient or inconsistent, glucose is fluctuating before a meal even begins. Trying to fine-tune a mealtime dose on top of an unstable background is like trying to tune a piano that keeps going out of tune on its own — each adjustment is undermined by the instability underneath it. Once basal insulin is titrated to keep fasting and overnight glucose consistently in target range, the problem reduces to meal coverage, and adjustments become far more predictable.
📊 Insulin Sequencing — The Evidence-Based Approach
Step 1 — Optimize basal first: Titrate long-acting insulin to achieve consistent fasting glucose in target range (typically 80–130 mg/dL). For Type 1, the ADA/EASD consensus recommends basal insulin as 30–50% of total daily insulin (40–60% with pump therapy). Adjust based on overnight and morning fasting glucose, not post-meal readings.
Step 2 — Address prandial coverage: Once fasting glucose is stable, adjust insulin-to-carbohydrate ratios and mealtime doses based on post-meal glucose readings. If post-breakfast glucose is consistently elevated but other meals are fine, the breakfast ICR needs adjustment — not the basal dose.
Step 3 — Fine-tune correction doses: Refine the insulin sensitivity factor (ISF) using correction response data. ISF is typically calculated as 1,800 ÷ total daily insulin dose (the "1,800 rule"), but individual response varies and real-world data from CGM provides the most accurate calibration.
Variability first: Before pushing for a lower A1c or higher TIR, ensure coefficient of variation is ≤36%. A CV above 36% predicts hypoglycemia risk independent of the average glucose — reducing variability first makes subsequent A1c improvement both safer and more achievable.
Hypoglycemia: Recognition and Response
Hypoglycemia — blood glucose below 70 mg/dL — is the most common acute complication of insulin therapy and of sulfonylurea use. It ranges from mild (symptomatic but self-treatable) to severe (requiring assistance from another person). Understanding the symptoms, the causes, and the response protocol is essential for anyone on insulin or a sulfonylurea.
Recognizing hypoglycemia
The early symptoms of hypoglycemia are driven by adrenaline release as the body detects falling glucose: shakiness, sweating, rapid heart rate, anxiety, and hunger. As glucose falls further, brain function is affected: confusion, difficulty concentrating, slurred speech, blurred vision, and — in severe cases — loss of consciousness or seizure. A critical complication is hypoglycemia unawareness — the loss of early warning symptoms after repeated hypoglycemic episodes, which means the first sign of low glucose may be confusion or unconsciousness rather than the adrenaline-driven warning symptoms.
The 15-15 rule for mild to moderate hypoglycemia
For glucose below 70 mg/dL with symptoms but the ability to eat and drink: take 15 grams of fast-acting carbohydrate, wait 15 minutes, and recheck glucose. If still below 70, repeat. Once glucose is above 70, eat a follow-up snack containing protein and carbohydrate if the next meal is more than an hour away, to prevent recurrence.
Fast-acting carbohydrate options include glucose tablets (4 tablets = 15g), 4 oz of juice or regular soda, or 1 tablespoon of honey. A practical and inexpensive alternative that many patients find more portable than glucose tablets: fruit snacks. A small pack of standard fruit snacks typically contains about 15–20g of fast-acting glucose and is easy to keep in a bag, desk, or car.
On fat-containing foods: chocolate, peanut butter, and similar fat-rich foods are not appropriate for the initial treatment of hypoglycemia. Fat slows gastric emptying and delays glucose absorption — the opposite of what you need when glucose is acutely low. The ADA explicitly recommends pure glucose or fast-acting carbohydrate as first-line treatment for this reason. However, fat-containing foods do have a role after the initial correction: a follow-up snack of protein and fat (cheese, peanut butter on a cracker) helps prevent recurrent hypoglycemia over the next few hours by providing a more sustained glucose contribution. In Type 1 diabetes specifically, protein stimulates glucagon release, which in turn drives the liver to release glucose — a useful mechanism for stabilizing glucose after correction when further hypoglycemia is a risk. The sequence matters: fast-acting carbohydrate first to correct, then protein and fat afterward to sustain.
🚨 Severe Hypoglycemia — When to Call for Help
Severe hypoglycemia occurs when someone cannot treat themselves — they are too confused, uncooperative, or unconscious to swallow safely. This is a medical emergency.
If the person is unconscious or cannot swallow: Do not give anything by mouth. Administer glucagon if available (intranasal glucagon — Baqsimi — or injectable glucagon kit) and call 911 immediately. Lay them on their side in case of vomiting.
Glucagon options: Intranasal glucagon (Baqsimi) — one spray in one nostril, no injection required. Injectable glucagon kits are available as auto-injectors (Gvoke, Zegalogue) or traditional mix-and-inject kits. All people on insulin should have a glucagon kit available at home, and household members should know how to use it.
After recovery: A severe hypoglycemic episode requires medical review. The cause — whether an insulin dose error, missed meal, unexpected exercise, or hypoglycemia unawareness — should be identified and addressed before resuming normal management.
Diabetic Ketoacidosis: Know the Warning Signs
Diabetic ketoacidosis (DKA) occurs when the body has severely insufficient insulin, forcing it to break down fat for fuel and producing acidic byproducts called ketones that accumulate in the blood. It is primarily a risk in Type 1 diabetes but can occur in Type 2, particularly during illness, surgery, or severe stress. It is life-threatening and requires emergency treatment.
DKA develops over hours to days, typically triggered by missed insulin doses, illness (which raises insulin requirements), or — less commonly — as the presentation of new Type 1 diabetes. The warning signs are recognizable and should prompt immediate action.
🚨 Signs of Diabetic Ketoacidosis — Go to the Emergency Room
Classic symptoms: Nausea and vomiting, abdominal pain, deep and rapid breathing (Kussmaul breathing), fruity-smelling breath, excessive thirst, frequent urination, extreme fatigue, confusion.
In numbers: Blood glucose typically above 250 mg/dL (though euglycemic DKA — DKA with near-normal glucose — can occur with SGLT2 inhibitor use). Urine or blood ketones elevated.
What to do: Go to the emergency room. Do not attempt to manage DKA at home. IV fluids, insulin, and electrolyte replacement are required and must be administered under medical supervision.
Sick day rules: During any illness — even a stomach bug — patients with Type 1 should never skip insulin entirely. Illness raises glucose and ketone production even without eating. Check glucose and ketones every 2–4 hours during illness, increase fluid intake, and contact your physician early if ketones are rising or glucose cannot be controlled.
Hyperosmolar Hyperglycemic State: The Type 2 Emergency
Hyperosmolar hyperglycemic state (HHS) is the Type 2 equivalent of DKA — a different but equally dangerous extreme of uncontrolled diabetes. It occurs when glucose rises to very high levels (often above 600 mg/dL) over days to weeks, causing severe dehydration as the body excretes glucose through the urine. Unlike DKA, ketoacidosis is usually mild or absent in HHS because the small amount of residual insulin in Type 2 prevents full fat breakdown — but the dehydration and electrolyte disturbances are severe and mortality is high.
HHS typically develops slowly and often in older adults who may not be drinking enough fluid. Symptoms include extreme thirst, very frequent urination, confusion, weakness, and — at its worst — coma. Any Type 2 patient with glucose consistently above 400 mg/dL, especially with confusion or inability to drink fluids, requires emergency evaluation.
>70%
Time-in-range target for most adults — the primary CGM goal, approximating A1c ~7%
+11%
Average time-in-range improvement with automated insulin delivery vs. standard pump therapy (meta-analysis)
≤36%
Target coefficient of variation — glucose variability above this threshold predicts hypoglycemia risk independently of A1c
25%
Reduction in all-cause hospitalization associated with CGM initiation in insulin-treated patients (Veterans Affairs study)
Sources & Further Reading
American Diabetes Association Professional Practice Committee. Pharmacologic approaches to glycemic treatment: Standards of Care in Diabetes — 2026. Diabetes Care. 2026;49(Suppl 1):S183–S215.
American Diabetes Association Professional Practice Committee. Diabetes technology: Standards of Care in Diabetes — 2026. Diabetes Care. 2026;49(Suppl 1):S150–S165.
American Diabetes Association Professional Practice Committee. Glycemic goals, hypoglycemia, and hyperglycemic crises: Standards of Care in Diabetes — 2026. Diabetes Care. 2026;49(Suppl 1):S132–S149.
Holt RIG, et al. The management of type 1 diabetes in adults: a consensus report by the ADA and EASD. Diabetes Care. 2021;44(11):2589–2625.
Maiorino MI, et al. Effects of continuous glucose monitoring on metrics of glycemic control in diabetes: a systematic review with meta-analysis of RCTs. Diabetes Care. 2020;43(5):1146–1156.
Karter AJ, et al. Association of real-time continuous glucose monitoring with glycemic control and acute metabolic events among patients with insulin-treated diabetes. JAMA. 2021;325(22):2273–2284.
Reaven PD, et al. Initiation of continuous glucose monitoring is linked to improved glycemic control and fewer clinical events in type 1 and type 2 diabetes in the Veterans Health Administration. Diabetes Care. 2023;46(4):854–863.
Yapanis M, et al. Complications of diabetes and metrics of glycemic management derived from continuous glucose monitoring. J Clin Endocrinol Metab. 2022;107(6):e2221–e2236.
Brown SA, et al. (Control-IQ). Six-month randomized, multicenter trial of closed-loop control in type 1 diabetes. N Engl J Med. 2019;381(18):1707–1717.
Collyns OJ, et al. (MiniMed 780G). Improved glycemic outcomes with Medtronic MiniMed advanced hybrid closed-loop delivery. Diabetes Care. 2021;44(4):969–975.
Wadwa RP, et al. Trial of hybrid closed-loop control in young children with type 1 diabetes. N Engl J Med. 2023;388(11):991–1001.
Di Molfetta S, et al. Efficacy and safety of different hybrid closed loop systems for automated insulin delivery in type 1 diabetes: a systematic review and network meta-analysis. Diabetes Metab Res Rev. 2024;40(6):e3842.
Sidki AS, et al. Hybrid closed-loop insulin delivery improves glycaemic control compared with sensor-augmented pump therapy: a meta-analysis of free-living randomised trials. Diabet Med. 2026. doi:10.1111/dme.70210.
Battelino T, et al. Clinical targets for continuous glucose monitoring data interpretation: recommendations from the international consensus on time in range. Diabetes Care. 2019;42(8):1593–1603.
Ceriello A, et al. Glycaemic variability in diabetes: clinical and therapeutic implications. Lancet Diabetes Endocrinol. 2019;7(3):221–230.
Kapur R, et al. Comparison of the efficacy and safety of rapid-acting insulin analogs, lispro versus aspart, in the treatment of diabetes: a systematic review of RCTs. Expert Opin Biol Ther. 2024;24(6):543–561.
Avgerinos I, et al. Ultra-rapid-acting insulins for adults with diabetes: a systematic review and meta-analysis. Diabetes Obes Metab. 2021;23(10):2395–2401.
Marso SP, et al. (DEVOTE). Efficacy and safety of degludec versus glargine in type 2 diabetes. N Engl J Med. 2017;377(8):723–732.
Madenidou AV, et al. Comparative benefits and harms of basal insulin analogues for type 2 diabetes: a systematic review and network meta-analysis. Ann Intern Med. 2018;169(3):165–174.
Xing X, et al. Therapeutic equivalence and switching between biosimilar and reference insulins: a systematic review and meta-analysis of RCTs. Diabetes Obes Metab. 2025. doi:10.1111/dom.70328.
Lipska KJ, et al. Association of initiation of basal insulin analogs vs NPH insulin with hypoglycemia-related emergency department visits or hospital admissions in type 2 diabetes. JAMA. 2018;320(1):53–62.
American Diabetes Association Professional Practice Committee. Glycemic goals, hypoglycemia, and hyperglycemic crises: Standards of Care in Diabetes — 2026. Diabetes Care. 2026;49(Suppl 1):S132–S149. [Hypoglycemia treatment protocol]
Dao GM, et al. The glycemic impact of protein ingestion in people with type 1 diabetes. Diabetes Care. 2025;48(4):509–518.
Muntis FR, et al. Pre-exercise protein intake is associated with reduced time in hypoglycaemia among adolescents with type 1 diabetes. Diabetes Obes Metab. 2024;26(4):1366–1375.
Kalergis M, et al. Impact of bedtime snack composition on prevention of nocturnal hypoglycemia in adults with type 1 diabetes. Diabetes Care. 2003;26(1):9–15.
Smart CE, et al. Both dietary protein and fat increase postprandial glucose excursions in children with type 1 diabetes, and the effect is additive. Diabetes Care. 2013;36(12):3897–3902.