Most of what goes wrong in type 2 diabetes happens years before blood sugar becomes abnormal. The driver is insulin itself — chronically elevated, quietly inflammatory, and largely invisible on the tests most people are given.
What insulin actually does
Insulin is widely described as the hormone that pushes glucose into cells by opening a channel. That description is incomplete enough to be misleading. Insulin is primarily a fat-storage hormone: it shifts metabolism away from using fat for energy and toward storing it.
In the absence of insulin the default state is lipolysis — fat is released from storage and converted into usable energy. In the presence of insulin, lipolysis stops and lipogenesis begins, converting circulating glucose into stored fat. The more insulin present, the more fat accumulates.
At the enzyme level, insulin activates hexokinase, which phosphorylates glucose and traps it inside the cell, and it inhibits glucose-6-phosphatase, which would otherwise release it. It also activates phosphofructokinase and glycogen synthase, driving glycogen synthesis. With an abundant glucose supply, the liver fills its glycogen stores quickly and converts the surplus onward into fat.
Insulin is the disease; glucose is the symptom
For type 2 diabetes to appear, two things must coexist: insulin resistance, and insulin secretion that has become inadequate relative to it. Overweight individuals commonly have insulin resistance without diabetes, because the pancreas compensates by producing more insulin. Diabetes only appears when that compensation fails.
The clinically important consequence is that the compensating period — hyperinsulinemia, before the collapse of insulin production — is not a safe waiting room. It is highly inflammatory, and significant tissue damage accumulates throughout it while fasting glucose still reads normal.
Why the eating pattern matters as much as the food
Most people eat from waking until bedtime: three meals, several snacks, and often sweetened drinks between. That pattern produces chronically high insulin production and fatigues the insulin receptors. Because insulin is a storage hormone, sustained elevation also drives fat accumulation in the liver, which generates further metabolic inflammation.
Giving the body an interval in which insulin is genuinely low is therefore not a fad. It is the mechanism by which stored energy becomes accessible again.
The link to inflammation
Hyperinsulinemia is the common link between adipose tissue inflammation and metabolic syndrome. The obesity-associated metabolic phenotype elevates pro-inflammatory cells — M1 macrophages and NK cells — while suppressing anti-inflammatory M2 macrophages, eosinophils and regulatory T cells. Notably, partially reducing circulating insulin attenuates excess-calorie-induced adipose tissue inflammation and improves insulin sensitivity, which points at insulin rather than fat mass as the operative variable. (Mol Cell Endocrinol. 2018 Dec 5;477:15-28.)
Under diabetic conditions, chronic hyperglycemia augments reactive oxygen species, which deteriorate beta-cell function and escalate insulin resistance further. The same process contributes to the atherosclerosis so commonly seen alongside diabetes.
Insulin resistance, not LDL, is the cardiovascular signal
Total and LDL cholesterol are poor markers of cardiovascular health. The pattern of elevated triglycerides with low HDL is considerably more predictive of cardiac risk, and it is a reliable marker of insulin resistance. The QRISK calculator, used to estimate ten-year cardiovascular risk, does not use LDL at all — it uses the total cholesterol to HDL ratio.
Preventing insulin resistance in young men would prevent an estimated 42% of myocardial infarctions — a larger reduction than correcting hypertension, at 36%.
An unrecognized cause of chronic pain
Metabolic inflammation from obesity and hyperinsulinemia is an under-recognized driver of pain. Musculoskeletal pain affects an estimated 13.5% to 47% of the general population, and roughly 75% of those affected report two or more painful areas. Multi-joint pain and its progression — including in non-weight-bearing joints — are linked independently to the inflammatory cascade rather than to mechanical load alone.
That independence is the point. A joint that bears no weight does not hurt because of body mass; it hurts because it is sitting in an inflammatory environment. A pain physician who never addresses insulin resistance is treating half the problem.
What reverses it
Weight loss and carbohydrate restriction are independent factors in reversing diabetes, and combining them works better than either alone. Weight loss contributes by decongesting the liver and pancreas, improving blood flow and reducing adipocyte hormonal signaling. Carbohydrate restriction contributes by lowering the insulin signal that drives storage in the first place.
The scale of the problem justifies the effort: as obesity has worsened worldwide, type 2 diabetes has followed, and one in every two Americans born today is predicted to develop it.
