Insulin resistance: how to recognize it and manage it through diet and lifestyle

Insulin resistance is a condition in which the body's cells become less responsive to insulin, the hormone that allows glucose to enter cells and be used as an energy source.

“When this response decreases, the pancreas has to produce larger amounts of insulin to keep blood glucose levels within the normal range,” explains Professor Rovere Querini. “Even if blood sugar levels still appear normal, the body's metabolism is already functioning in a state of imbalance.”

The link between insulin resistance, weight gain, and diabetes

High insulin and blood glucose levels promote the accumulation of visceral fat—fat stored around the abdominal organs. This fat releases inflammatory substances that interfere with both glucose and fat metabolism.

“This creates a vicious cycle,” the specialist explains. “Abdominal fat further reduces insulin sensitivity, while excess insulin encourages the body to store more energy as fat. As a result, body weight tends to increase, and blood sugar levels may gradually rise until prediabetes develops.”

This condition is also frequently associated with:

• elevated triglycerides;
• reduced HDL ("good") cholesterol;
• high blood pressure;
• hepatic steatosis, commonly known as fatty liver disease.

In its early stages, insulin resistance does not always produce noticeable symptoms. However, several signs may suggest an underlying metabolic imbalance and should not be overlooked:

• increasing waist circumference;
• difficulty losing weight;
• feeling sleepy after meals;
• frequent hunger;
• cravings for sugary foods;
• persistent fatigue;
• high blood pressure;
• elevated triglycerides;
• a diagnosis of fatty liver disease.

Some people may also develop darkened patches of skin, particularly on the neck, under the arms, or in the groin.

In women, insulin resistance may also be associated with:

• polycystic ovary syndrome (PCOS);
• irregular menstrual cycles;
• acne;
• excessive body hair growth (hirsutism).

While these signs alone cannot confirm the diagnosis, they indicate the need for a thorough clinical and metabolic evaluation.

The factors most commonly associated with insulin resistance include:

• overweight and obesity;
• excess abdominal fat;
• physical inactivity;
• a family history of type 2 diabetes;
• a diet high in simple sugars and ultra-processed foods;
• insufficient sleep;
• obstructive sleep apnea;
• chronic stress.

Reduced muscle mass also plays an important role. Muscle tissue is one of the body's primary consumers of glucose and is essential for maintaining healthy blood sugar levels.

“Diagnosis is based on a combination of medical history, physical examination, body measurements, and laboratory tests,” Professor Rovere Querini explains.

During the assessment, physicians evaluate:

• body weight;
• body mass index (BMI);
• waist circumference;
• blood pressure;
• body composition;
• metabolic profile.

The most commonly requested laboratory tests include:

• fasting blood glucose;
• fasting insulin;
• glycated hemoglobin (HbA1c);
• lipid profile;
• liver enzymes (transaminases);
• an oral glucose tolerance test (when indicated).

The following values indicate prediabetes:

• fasting blood glucose between 100 and 125 mg/dL;
• HbA1c between 5.7% and 6.4%;
• blood glucose between 140 and 199 mg/dL two hours after an oral glucose tolerance test.

To assess insulin resistance, physicians may also calculate the HOMA-IR index, obtained by multiplying fasting blood glucose by fasting insulin and dividing the result by 405. Values above 2.5 generally indicate reduced insulin sensitivity.

Lifestyle modification is the cornerstone of treatment. Even modest weight loss can significantly improve insulin sensitivity, especially when it reduces visceral fat. From a nutritional perspective, the recommended diet should emphasize:

• vegetables;
• legumes;
• whole grains;
• whole fruit;
• fish;
• extra virgin olive oil;
• high-quality protein sources.

It is advisable to limit:

• sugary drinks;
• sweets;
• snack foods;
• excessive alcohol consumption;
• ultra-processed foods.

Physical activity plays a direct role in improving glucose metabolism. Aerobic exercise increases glucose uptake by muscles, while strength training helps preserve muscle mass and supports long-term metabolic health. Regular sleep, appropriate treatment of sleep apnea, and reducing sedentary behavior are also important for improving metabolic function.

“When cardiovascular or metabolic risk is particularly high, the physician may consider specific treatments to help control body weight, blood glucose, blood pressure, cholesterol levels, or fatty liver disease,” Professor Rovere Querini concludes.

The Metabolic Health Center at IRCCS Ospedale San Raffaele offers a multidisciplinary evaluation, on a private-pay basis, for the diagnosis and management of conditions associated with metabolic dysfunction, including:

• overweight and obesity;
• insulin resistance;
• abnormal blood glucose levels;
• dyslipidemia;
• arterial hypertension;
• fatty liver disease.

The center combines medical and nutritional expertise to identify risk factors early and develop personalized prevention and treatment strategies tailored to each patient.