Insulin Resistance and Metabolic Syndrome: Symptoms and Diagnosis
Fatigue after meals, a belly that won't shift despite dieting, constant sugar cravings, and a sense that your body just isn't cooperating — these can all be signs of insulin resistance. According to the WHO, metabolic syndrome — a condition closely linked to insulin resistance — affects one in four adults worldwide. Yet most people are unaware of the problem until it progresses to type 2 diabetes or cardiovascular disease. This article explains what happens in the body and how to catch it early.
What insulin resistance is in plain language
Insulin is a hormone produced by the pancreas that acts as a "key": it unlocks cells for glucose (sugar), allowing it to enter and be used as energy. Normally, after a meal, blood glucose rises, the pancreas releases insulin, cells "open up", glucose is absorbed — and blood sugar returns to normal.
With insulin resistance, cells stop responding properly to insulin — as if the lock has rusted and the key won't turn. The pancreas is forced to produce more and more insulin to push glucose into the cells. At first this compensates for the problem, but over time the pancreas becomes exhausted and blood sugar starts to rise. First comes prediabetes, then type 2 diabetes.
Insulin resistance develops gradually over years. Its main causes: excess weight (especially visceral fat — fat around the internal organs), sedentary lifestyle, chronic stress, poor sleep, a diet high in refined carbohydrates, and genetic predisposition.
Symptoms: belly fat, fatigue, sugar cravings
Insulin resistance produces no obvious symptoms for a long time — which is why it is often discovered incidentally through blood tests. But there are indirect signs worth knowing:
- Abdominal obesity — fat accumulates mainly around the abdomen. A waist circumference above 94 cm in men and 80 cm in women is one of the key criteria for metabolic syndrome.
- Fatigue after meals — especially after carbohydrate-rich food. The body cannot use glucose efficiently, leaving a person feeling sluggish and drowsy 1–2 hours after eating.
- Constant cravings for sugar and carbohydrates — the brain "demands" quick energy because cells are starved despite high blood glucose levels.
- Difficulty losing weight — high insulin blocks fat breakdown (lipolysis). Even with calorie restriction, weight loss is slow or absent.
- Dark skin patches (acanthosis nigricans) — velvety dark areas in skin folds (neck, armpits, groin). A direct sign of hyperinsulinaemia — excess insulin in the blood.
- Elevated blood pressure — insulin causes sodium and water retention, raising blood pressure.
- In women — irregular periods, excess hair growth, acne (signs of polycystic ovary syndrome, which is closely linked to insulin resistance).
Metabolic syndrome — when several problems occur together
Metabolic syndrome is not a single disease but a cluster of metabolic abnormalities that together sharply increase the risk of type 2 diabetes and cardiovascular disease. The diagnosis is made when three or more of the following criteria are present (IDF/AHA/NHLBI guidelines):
- Waist circumference: above 94 cm in men, above 80 cm in women (European criteria);
- Triglycerides: 1.7 mmol/L or higher (or taking triglyceride-lowering medication);
- HDL cholesterol ("good" cholesterol): below 1.0 mmol/L in men, below 1.3 mmol/L in women;
- Blood pressure: 130/85 mmHg or higher (or taking antihypertensive medication);
- Fasting glucose: 5.6 mmol/L or higher (or already diagnosed type 2 diabetes).
Metabolic syndrome increases the risk of type 2 diabetes fivefold and the risk of heart attack and stroke two to threefold. Yet it is fully reversible in the early stages: lifestyle changes can normalise all indicators without medication.
Tests for diagnosis (with reference ranges)
Several blood tests are used to diagnose insulin resistance and metabolic syndrome. Here are the key indicators and their normal ranges:
Fasting glucose: normal — below 5.6 mmol/L. A level of 5.6–6.9 mmol/L indicates prediabetes (impaired fasting glucose). 7.0 mmol/L or above on two separate measurements — diabetes.
Glycated haemoglobin (HbA1c): reflects average blood sugar over the past 2–3 months. Normal — below 5.7%. Level 5.7–6.4% — prediabetes. 6.5% or above — diabetes.
Fasting insulin: normal — 3–25 mU/L (in most laboratories). A level above 25 mU/L with normal blood sugar is a sign of hyperinsulinaemia and insulin resistance.
HOMA-IR index (Homeostatic Model Assessment of Insulin Resistance) — a calculated measure of insulin resistance. Formula: HOMA-IR = (fasting glucose in mmol/L × fasting insulin in mU/L) / 22.5. Normal — up to 2.7. A value above 2.7 indicates insulin resistance.
Lipid profile: triglycerides (normal below 1.7 mmol/L), HDL cholesterol (normal above 1.0 in men and above 1.3 in women), LDL cholesterol (normal below 3.0 mmol/L in the absence of cardiovascular disease).
Additional tests may include: C-peptide (pancreatic function), oral glucose tolerance test (OGTT), ALT and AST (fatty liver disease is a common comorbidity), TSH (to rule out hypothyroidism as a cause of metabolic disturbance).
If you're experiencing the symptoms described above, try describing them to our assistant — this helps identify which tests to prioritise.
What to do about insulin resistance
The good news: insulin resistance in the early stages is fully reversible. The main tools are lifestyle changes.
Diet. Reducing fast carbohydrates (sugar, white bread, pastries, sweet drinks) is the key step. Focus on fibre, protein, and healthy fats. The Mediterranean diet and a low glycaemic index diet have shown the best results for insulin resistance. Losing 5–10% of body weight already significantly improves insulin sensitivity.
Physical activity. Muscles are the body's main consumers of glucose. Regular aerobic exercise (150 minutes per week of moderate intensity) and strength training (2–3 times per week) reduce insulin resistance independently of weight change. Even a 30-minute walk after a meal lowers post-meal blood glucose by 20–30%.
Sleep. Chronic sleep deprivation (less than 7 hours) itself causes insulin resistance. Normalising sleep is an essential part of treatment.
Medication. For prediabetes and metabolic syndrome, a doctor may prescribe metformin — a drug that increases cell sensitivity to insulin. It is not insulin and does not lower blood sugar below normal. Newer drug classes — GLP-1 receptor agonists (semaglutide, liraglutide) — are also used; they reduce weight and improve glycaemic control.
To find an endocrinologist or dietitian, use the doctor routing tool.
Frequently asked questions
Can insulin resistance be identified by external signs?
Partly — yes. Abdominal obesity (a large belly with otherwise normal weight), dark velvety patches in skin folds (acanthosis nigricans), constant sugar cravings, and fatigue after meals are indirect signs. But an accurate diagnosis requires blood tests: fasting glucose, fasting insulin, and the HOMA-IR index.
Is insulin resistance the same as diabetes?
No. Insulin resistance is a precursor to type 2 diabetes, not diabetes itself. With normal blood glucose and elevated insulin, a diabetes diagnosis is not made. This is precisely the moment when lifestyle changes can prevent diabetes from developing. The DPP study showed that lifestyle intervention reduces diabetes risk by 58%.
What is the normal fasting insulin level?
The normal range for fasting insulin is 3–25 mU/L. However, an optimal level is considered to be below 10–12 mU/L. A level above 25 mU/L with normal blood sugar is a sign of hyperinsulinaemia. Reference ranges may vary slightly between laboratories.
What is the HOMA-IR index and how is it interpreted?
HOMA-IR is a calculated index of insulin resistance. Normal — up to 2.7. A value of 2.7–4.0 indicates moderate insulin resistance. Above 4.0 — marked insulin resistance. Two fasting measurements taken simultaneously are needed: glucose (mmol/L) and insulin (mU/L). Formula: (glucose × insulin) / 22.5.
Are insulin resistance and polycystic ovary syndrome (PCOS) related?
Yes, very closely. Insulin resistance is found in 50–70% of women with PCOS. High insulin stimulates the ovaries to produce excess androgens (male hormones), leading to irregular periods, acne, and excess hair growth. Treating insulin resistance (metformin, lifestyle changes) improves PCOS symptoms.
Can insulin resistance be reversed without medication?
In the early stages — yes. A 7–10% weight reduction, regular physical activity, and dietary changes normalise insulin sensitivity in most people without drugs. This is confirmed by large clinical trials. Medications (metformin, GLP-1 agonists) are prescribed when lifestyle changes are insufficient or when diabetes risk is high.
Symptomatica is an informational reference service. Not a medical service; does not diagnose or prescribe treatment. For any symptoms, please consult a doctor.