Insulin Resistance
Insulin resistance means cells respond less effectively to insulin, forcing the pancreas to produce more of it to keep blood sugar normal -- the metabolic starting point behind prediabetes, type 2 diabetes, PCOS, and much of metabolic syndrome, evaluated per the American Diabetes Association (ADA) 2026 Standards of Care.
Symptoms
Often none directly -- insulin resistance itself doesn't cause symptoms until it progresses far enough to raise blood sugar. Some people notice skin changes (acanthosis nigricans, darkened skin folds) or difficulty losing weight despite effort.
Causes and risk
Excess visceral fat, inactivity, genetics, and chronic stress all drive insulin resistance; it clusters with PCOS, sleep apnea, and fatty liver disease.
How it is evaluated
HOMA-IR is used mainly in research settings rather than as a universal diagnostic tool -- reported cutoffs vary widely across populations, per population-based cutoff research, and fasting insulin assays are not standardized. The ADA instead recommends screening for the downstream conditions (prediabetes, diabetes) using A1c, fasting glucose, or an oral glucose tolerance test.
Treatment
Lifestyle intervention is more effective than medication and is first-line, per the ADA 2026 Standards of Care; metformin is reserved for higher-risk groups (BMI 35+, younger adults, prior gestational diabetes, or higher baseline glucose/A1c) as an off-label use for diabetes prevention specifically.
When to seek care
Symptoms of very high blood sugar -- excessive thirst, frequent urination, confusion, or fruity-smelling breath -- can signal diabetic ketoacidosis or a hyperglycemic crisis and require emergency evaluation, per ADA 2026 guidance on hyperglycemic crises.