What is insulin resistance?
Insulin resistance (IR) is a subnormal biological response to normal concentrations of insulin. In clinical practice, it means that a given concentration of insulin produces a less‑than‑expected glucose‑lowering effect. IR is a key driver of metabolic syndrome — a cluster of central obesity, hyperglycemia, dyslipidemia, and hypertension — and it significantly increases the risk of type 2 diabetes and cardiovascular disease.
Core mechanisms (brief)
- Visceral adipose tissue (VAT) releases excess free fatty acids (FFA) and pro‑inflammatory cytokines (TNF‑α, IL‑6), while reducing adiponectin.
- These factors impair insulin receptor signalling, especially through serine phosphorylation of IRS‑1.
- Endothelial dysfunction (reduced nitric oxide, increased inflammation) is a critical component.
Prevalence & susceptibility
- Women are disproportionately affected: in some cohorts IR prevalence is ~53.8% in females vs 29.2% in males.
- Perimenopausal women (42–59 y) saw IR prevalence rise from 22.5% to 30.2% between 2003–2023.
- Even normal‑weight women show IR (12.62%) more often than normal‑weight men (8.55%).
- Risk factors: obesity, physical inactivity, poor diet, smoking, poor sleep, family history, age >45, ethnicity (African American, Hispanic, Native American, Asian), PCOS, medications (glucocorticoids, antipsychotics), and gestational diabetes.
📌 Key takeaway: IR is highly prevalent, especially in women, and it is driven by visceral fat, inflammation, and lifestyle factors. Early recognition is critical to prevent progression to type 2 diabetes.