Insulin resistance itself causes no direct symptoms. The signs that suggest it are a waist larger than half your height, darkened velvety skin in the neck folds or armpits, skin tags, high triglycerides with low HDL, rising blood pressure, intense hunger or an energy slump a few hours after carbohydrate-heavy meals, fatty liver, and — in women — irregular periods or features of PCOS. Any of these is a reason to ask for a fasting glucose and A1C.
Why the signs are indirect
Insulin resistance means cells respond weakly to insulin. The pancreas compensates by producing more, and for years that extra insulin keeps blood glucose normal. So a glucose test — the thing most people think of as "checking for diabetes" — stays reassuring long after the underlying problem has begun.
What does change during those years is everything that high insulin levels and impaired fat handling affect: where fat is stored, blood fats, blood pressure, skin, appetite, and hormones. The signs below are those effects.
Physical signs
A large waist
The single most useful sign. Visceral fat — fat around the abdominal organs — both causes and results from insulin resistance. A waist circumference above 40 inches (102 cm) in men or 35 inches (88 cm) in women is the usual threshold; a simpler rule is that waist should be less than half of height. Thresholds are lower for people of South and East Asian ancestry, who develop insulin resistance at smaller waists.
Darkened, velvety skin in body folds
Acanthosis nigricans is a thickening and darkening of skin on the back of the neck, in the armpits, groin, elbows or knuckles. It is caused directly by high insulin stimulating skin cells and is one of the most specific visible signs of insulin resistance. It is more common in people with darker skin and in children and adolescents with obesity.
Skin tags
Small, soft skin growths in the neck, armpits or groin are associated with insulin resistance, probably through the same mechanism. Many people with skin tags do not have insulin resistance, but multiple skin tags together with a large waist raise the likelihood.
Fatty liver
Fat accumulating inside the liver is both a consequence and a driver of insulin resistance. It is usually silent and found incidentally on an ultrasound or through mildly raised liver enzymes (ALT, AST) on a routine blood test.
Laboratory signs
Even before glucose rises, routine blood tests often show a characteristic pattern:
- High triglycerides (above 150 mg/dL, 1.7 mmol/L)
- Low HDL cholesterol (below 40 mg/dL in men, 50 mg/dL in women)
- A triglyceride-to-HDL ratio above about 3 (when both are in mg/dL), a reasonable indirect marker of insulin resistance
- Fasting glucose in the upper-normal range and rising year on year
- Mildly raised liver enzymes
- High uric acid, which travels with insulin resistance and gout
- Raised fasting insulin, if it is measured
Together with rising blood pressure, this pattern is the basis of metabolic syndrome.
How it feels
Hunger and energy dips after meals
After a large carbohydrate-heavy meal, an insulin-resistant person produces a large, delayed surge of insulin. Glucose rises high and then, two to four hours later, may fall quickly, producing hunger, shakiness, irritability and a strong desire for more carbohydrate. Many people describe this as an afternoon slump.
Difficulty losing weight
High insulin promotes fat storage and inhibits the release of stored fat, so weight loss can feel harder than it should, particularly around the middle.
Fatigue and brain fog
Common, non-specific, and difficult to attribute to insulin resistance alone — but frequently reported and often improved when insulin sensitivity improves.
Signs in women
Insulin resistance is central to polycystic ovary syndrome (PCOS). High insulin stimulates the ovaries to produce excess androgens, which cause irregular or absent periods, acne, excess facial or body hair, and thinning scalp hair. Difficulty conceiving, a history of gestational diabetes, or having delivered a baby over 9 pounds are also associated with insulin resistance.
What to do if you recognise these signs
None of these signs is a diagnosis. Their value is in prompting a test. Ask your doctor for a fasting glucose, an A1C, a lipid panel and a blood pressure check. If results are in the normal range but the signs are present, the response is the same as for prediabetes: reduce waist fat, move more, sleep more consistently, and re-test in a year. Insulin sensitivity improves quickly with those changes, and the signs above — including the skin changes — often recede.
Frequently asked questions
Can insulin resistance be diagnosed from symptoms alone?
No. The signs on this page raise the likelihood; a fasting glucose, A1C, lipid panel and sometimes fasting insulin confirm the picture. Several signs together are more telling than any one.
Are sugar cravings a sign of insulin resistance?
They can be, though they have many other causes. In insulin resistance, high insulin after a carbohydrate-rich meal can push glucose down quickly a few hours later, producing hunger and a craving for more carbohydrate.
Does insulin resistance cause weight gain, or the other way round?
Both. Excess visceral fat causes insulin resistance, and the resulting high insulin promotes further fat storage and blocks fat release. Breaking the loop from either side helps.
References
- NIDDK. Insulin Resistance & Prediabetes (2023). https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/prediabetes-insulin-resistance
- National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK). Type 2 Diabetes (2023). https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes/type-2-diabetes
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