The Problem With "High Blood Sugar"
First, a clarifying note on the name. The full medical term is diabetes mellitus — from the Greek diabainein ("to pass through") and the Latin mellitus ("honeyed" or "sweet"). The name dates to ancient physicians who noticed that the urine of affected patients was sweet — a result of glucose spilling into the urine when blood levels become too high. You may occasionally hear the term diabetes insipidus, which sounds related but is an entirely different condition involving a different hormone and the kidneys' handling of water. It has nothing to do with blood sugar, insulin, or anything covered in this series. When people say "diabetes," they generally mean diabetes mellitus.
Most people understand diabetes mellitus as a blood sugar problem. That's true, but it's about as useful as describing pneumonia as "a breathing problem." It's not wrong — it just doesn't tell you why it's happening, what's driving it, or what you can actually do about it.
Diabetes is a disorder of how your body produces, uses, and responds to insulin — a hormone made by specialized cells in the pancreas (beta cells) that acts as a key, unlocking your body's cells so glucose can enter and be used for energy. When that system breaks down — whether because the key is missing, the lock stops working, or both — glucose accumulates in the bloodstream instead of fueling your tissues. The downstream consequences of that accumulation, sustained over years, are what cause the complications most people associate with the disease.
However, the mechanisms behind that breakdown are profoundly different depending on which type of diabetes you have. And so are the treatments, the risks, and — critically — how much your own choices can shape the trajectory of the disease.
How the Glucose-Insulin Axis Works
When you eat a meal containing carbohydrates, your digestive system breaks them down into glucose, which enters the bloodstream. Your pancreas detects rising blood glucose and releases insulin in response. Insulin travels through the bloodstream and binds to receptors on the surface of cells — particularly in muscle, fat, and the liver — signaling them to take up glucose and either use it for immediate energy or store it for later (primarily as glycogen in the liver and muscle, or as fat).
At the same time, insulin suppresses the liver from releasing glucose it has stored — a process called gluconeogenesis. This is important: your liver is constantly producing glucose even when you haven't eaten. Insulin keeps that production in check. When insulin signaling fails, the liver keeps pumping out glucose even when blood levels are already high — adding fuel to an already overloaded system.
In diabetes, this loop breaks — at different points and for different reasons depending on the type. That's the subject of the next post. But understanding the loop itself is the foundation for everything else in this series.
Why Lifestyle Moves the Needle More Than Most Drugs
Here's what I tell patients who have just been diagnosed: the most powerful tools you have are not in a prescription pad. I've seen patients cut their A1c by 5 or 6 points — from levels that were causing active organ damage to levels in the normal or near-normal range — through a few well-chosen medications tailored to their situation and genuine lifestyle change. That kind of result is not typical, but it is real, and it's seen far more often with lifestyle engagement than without it.
The reason is mechanistic. Skeletal muscle is the largest glucose-consuming tissue in the body, responsible for roughly 80% of insulin-stimulated glucose uptake. Exercise — particularly resistance training — directly increases the density and activity of glucose transporters (GLUT4 transporters) in muscle cells, improving insulin sensitivity independent of weight loss. Diet composition changes the glucose load the system has to handle in the first place. And weight loss, even modest amounts, dramatically reduces the inflammatory signaling from fat tissue (adipose-derived cytokines) that drives insulin resistance in Type 2 diabetes.
Medications work on top of that environment. When the environment is hostile — high-carbohydrate diet, sedentary lifestyle, excess visceral fat — medications are fighting uphill. When the environment improves, the same medications work better, and sometimes you need fewer of them.
The patients I've seen achieve the most dramatic turnarounds share a common pattern: they stopped thinking of diabetes as a condition to be managed and started thinking of it as a lifestyle. That reframe changes everything about how they approach food, movement, and medication. I don't promise any particular result — biology is individual — but the direction is reliably the same: lifestyle engagement makes everything else work better.
How Common Is Diabetes?
Diabetes is not rare. In the United States, approximately 38 million people have diabetes — about 11.6% of the population. Another 98 million adults have pre-diabetes, a state of impaired glucose regulation that substantially increases the risk of progressing to Type 2 diabetes and carries its own cardiovascular risk. Roughly 1 in 5 people with diabetes don't know they have it.
Type 2 diabetes accounts for 90–95% of all cases. Type 1 accounts for roughly 5–10%. The remainder — LADA, MODY, gestational diabetes, and Type 3c — are less common but frequently misdiagnosed, with real consequences for how they're treated. We'll cover all of them in Post 2.
Three Myths Worth Clearing Up Now
Before getting into the types, mechanisms, and treatments, there are a handful of persistent misconceptions that color how patients understand their diagnosis — and in some cases, how they make decisions. I'd rather address them directly than have them run silently in the background. More myth cards appear in later posts where they're most relevant — in the treatment and diet sections especially.
Common Diabetes Myths — and What the Evidence Actually ShowsWhat This Series Covers
Each post in this series is designed to give you the information you need to have a real conversation with your doctor — not to replace that conversation, but to make it more productive. We'll go deep on the biology, honest about what the evidence shows and where it's weak, and specific about what you can actually do.