Insulin resistance does not hurt, but over the years it can turn into prediabetes and type 2 diabetes. The good news is that this is one of the most manageable metabolic conditions: lifestyle can significantly reduce the risk. The editors tell what is proven to work for prevention, what tests help to assess glucose metabolism and when it is time to go to the doctor.
Prevention: What's Proven to Work
The strongest evidence for prevention of glucose metabolism disorders comes from large randomised trials. The Finnish Diabetes Prevention Study (Tuomilehto et al., 2001) and the US Diabetes Prevention Program (Knowler et al., 2002) found that lifestyle changes—modest weight loss, regular physical activity, and dietary modification—reduced the risk of progression from impaired glucose tolerance to diabetes by approximately 58%.
In DPP, metformin also reduced the risk, but less than lifestyle changes (by approximately 31%). For athletes, this is an important reminder: no pill can replace regular exercise. Metformin is a prescription drug, its prescription is decided by the doctor if there are indications.
The American Diabetes Association's position statement on physical activity (Colberg et al., 2016) recommends combining aerobic and strength-based activities and avoiding long breaks between workouts, as the effect of each session on insulin sensitivity is temporary. It is also helpful to break up long periods of sitting with short periods of movement.
For active people, two periods are especially important: the off-season and the end of the career. That's when energy expenditure drops, and eating habits remain. A gradual reduction in calories, maintaining at least 2-3 workouts per week and controlling the waist circumference help to avoid "metabolic kickback".
Nutrition for an athlete without unnecessary myths
Insulin resistance is not treated by complete rejection of carbohydrates. For athletes, carbohydrates are the main fuel for intensive work, and glycogen in the muscles after training is restored precisely at the expense of glucose. The question is not whether to eat carbohydrates, but in their quantity relative to the load, quality and time of consumption.
- Build your diet on whole grains, legumes, vegetables and fruits, not sweets and sugary drinks.
- Tie the main share of carbohydrates to training; on rest days reduce it.
- Avoid long-term, significant caloric surplus when gaining weight.
- Provide enough protein and dietary fibre to keep you full.
- Limit alcohol: it adds calories and worsens the fatty liver.
Gaining muscle mass is possible without "dirty" mass gain. A moderate calorie surplus together with the right program allows you to gain muscle with less fat gain. Rapid weight gain, especially in the abdominal area, is a signal that the surplus is too large.
Regarding supplements: the evidence base for “insulin sensitizers” like chromium, cinnamon, or berberine is patchy, and their effects are much smaller than those of exercise and weight control. They cannot compensate for excess calories or the effects of hormonal drugs. Berberine also interacts with many medications.
Sleep is also part of the "nutrition" of metabolism. Chronic sleep deprivation impairs glucose tolerance and increases appetite. Prioritizing 7-9 hours of sleep often does more than another diet change.
Diagnostics: what tests to take
In clinical practice, the diagnosis of "insulin resistance" as a separate disease is not made - instead, glucose metabolism and associated risk factors are assessed. The criteria for prediabetes and diabetes are defined in the annual Standards of Medical Care of the American Diabetes Association.
| Indicator | Normal range | Prediabetes | Diabetes |
|---|---|---|---|
| Fasting plasma glucose | < 5.6 mmol/l | 5.6–6.9 mmol/l | ≥ 7.0 mmol/l |
| HbA1c | < 5,7% | 5,7â6,4% | ⥠6,5% |
| Glucose 2 hours after 75 g oral glucose (OGTT) | < 7.8 mmol/l | 7.8–11.0 mmol/l | ≥ 11.1 mmol/l |
The HOMA-IR index, proposed by Matthews et al. (1985), is calculated based on fasting glucose and insulin levels. It is useful in research and for dynamic surveillance, but does not have a universal diagnostic cutoff: laboratories and populations use different thresholds. The "gold standard" for assessing insulin sensitivity is the hyperinsulinemic euglycemic clamp (DeFronzo et al., 1979), but this is an investigational procedure.
The doctor also pays attention to clinical signs: waist circumference, blood pressure, lipid profile (high triglycerides and low HDL), signs of fatty liver disease by ultrasound or liver tests, as well as acanthosis nigricans — dark velvety areas of skin on the neck or armpits. In athletes using steroids, lipid changes should be interpreted taking into account the drugs.
In order for the tests to be informative, take them on an empty stomach after 8-12 hours without food, not after very intense training the day before and not against the background of an acute illness. Taking glucocorticoids, growth hormone or insulin changes the results, so it is necessary to inform the doctor about them.
When to consult a doctor
Urgent help is required for symptoms of pronounced hyperglycaemia — strong thirst, frequent urination, rapid weight loss, nausea, the smell of acetone from the mouth, confusion — as well as for signs of hypoglycaemia on the background of insulin: sweating, trembling, confusion, convulsions. Severe hypoglycaemia can be fatal.
Planned consultation with a therapist or endocrinologist is indicated if fasting glucose or HbA1c falls into the prediabetes range, if there is excess weight with a waist circumference above the recommended, type 2 diabetes in close relatives, a history of gestational diabetes, polycystic ovary syndrome, or elevated blood pressure and triglycerides.
Separately, we recommend that athletes who used growth hormone, glucocorticoids, or anabolic steroids, as well as former strength athletes after the end of their careers, be examined. Even without symptoms, basic tests once a year help to notice changes at an early stage.
During the consultation, it is important to talk about the training regime and nutrition. A doctor who knows that a patient is exercising every day will evaluate things like creatinine or liver enzymes differently and create a realistic prevention plan.
Editorial conclusions
Insulin resistance is best prevented by regular aerobic and strength training, visceral fat control, good nutrition and adequate sleep. Large studies have shown that lifestyle changes reduce the risk of diabetes by approximately 58%.
Fasting glucose, HbA1c and tolerance test are used to assess glucose metabolism; HOMA-IR is an auxiliary indicator without a universal limit.
Results in the prediabetes range, family history of diabetes, obesity, or experience with hormone use are reasons for consulting a doctor.
The editors also recommend reading our materials on the causes of insulin resistance in athletes, on nutrition during weight gain, and on the risks of growth hormone.
List of used literature
- Tuomilehto J, Lindström J, Eriksson JG, et al. Prevention of type 2 diabetes mellitus by changes in lifestyle among subjects with impaired glucose tolerance. N Engl J Med. 2001;344(18):1343â1350.
- Knowler WC, Barrett-Connor E, Fowler SE, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. N Engl J Med. 2002;346(6):393â403.
- Colberg SR, Sigal RJ, Yardley JE, et al. Physical activity/exercise and diabetes: a position statement of the American Diabetes Association. Diabetes Care. 2016;39(11):2065â2079.
- American Diabetes Association Professional Practice Committee. Standards of Care in Diabetesâ2024. Diabetes Care. 2024;47(Suppl 1).
- Matthews DR, Hosker JP, Rudenski AS, et al. Homeostasis model assessment: insulin resistance and beta-cell function from fasting plasma glucose and insulin concentrations in man. Diabetologia. 1985;28(7):412â419.
- DeFronzo RA, Tobin JD, Andres R. Glucose clamp technique: a method for quantifying insulin secretion and resistance. Am J Physiol. 1979;237(3):E214âE223.
