Insulin is the key that unlocks cells to absorb glucose from the bloodstream. In Type 2 diabetes, that key still exists — but the locks (insulin receptors) have become resistant. The pancreas compensates by producing more insulin. Over years, this compensatory hyperinsulinemia eventually exhausts the pancreatic beta cells, and insulin production declines. The result: chronic hyperglycemia and its downstream organ damage.
Insulin resistance is driven by multiple factors: excess adipose tissue (particularly visceral fat), physical inactivity, chronic inflammation, genetic predisposition, sleep deprivation, and hormonal dysregulation. The adipose tissue itself — particularly omentum fat — secretes pro-inflammatory adipokines that directly worsen insulin receptor signaling. This is why visceral fat is metabolically dangerous in ways that subcutaneous fat is not.
The diagnostic criteria for diabetes are: fasting glucose ≥126 mg/dL, 2-hour glucose ≥200 mg/dL on OGTT, HbA1c ≥6.5%, or random glucose ≥200 with symptoms. Prediabetes (HbA1c 5.7–6.4%) represents a critical intervention window — progression to diabetes is not inevitable if lifestyle changes are implemented. The Diabetes Prevention Program showed that intensive lifestyle intervention reduced diabetes incidence by 58%.
Metformin remains first-line pharmacotherapy for Type 2 diabetes — safe, inexpensive, effective, and associated with possible longevity benefits beyond glycemia. GLP-1 receptor agonists (semaglutide, tirzepatide) and SGLT2 inhibitors have transformed the treatment landscape, offering cardiovascular and renal protection independent of glucose lowering. Treatment selection now considers comorbidities, weight, cost, and patient preference — not just HbA1c.