Insulin Sensitivity, Blood Glucose, and Diabetes

"There is a single number, measured from a drop of blood, that predicts more about your long-term health than almost any other: your blood glucose. Keep it in its narrow, healthy range and the machinery of metabolism hums quietly in the background. Let it drift upward for years — as it now does in a large fraction of the population — and it silently corrodes the eyes, kidneys, nerves, and arteries. This book is about that number: what controls it, why it goes wrong, and how — through food, movement, sleep, and weight — it can usually be brought back into balance."

Blood-glucose regulation sits at the center of metabolic health. The hormone that controls it, insulin, is the body's master anabolic (storage and growth) signal, so its dysfunction radiates outward into nearly every chronic disease of affluence: type 2 diabetes, cardiovascular disease (Books A5, I1), fatty liver, polycystic ovary syndrome, and even some cancers and dementias are linked to insulin resistance. Understanding this one system explains an enormous amount about modern health — why type 2 diabetes has become a global epidemic, why prediabetes is so common and so under-recognized, why diet and exercise are genuinely powerful "medicine" here (more so than for almost any other condition), and why kidney failure, blindness, amputations, and heart attacks so often trace back to years of elevated glucose. It is also the area of nutrition most saturated with hype and misinformation — "glucose spikes," continuous glucose monitors marketed to healthy people, "blood-sugar-balancing" supplements, and viral "anti-spike" tricks. This book gives you the real physiology so you can separate genuine, evidence-based metabolic health from marketing — whether you are managing your own glucose, supporting your training, or guiding others.