What is insulin resistance, and its signs?

Insulin resistance means the body's cells respond less than they should to the hormone insulin, so the pancreas has to make more of it to keep blood sugar in the normal range. Often it is silent for years, but it may show up through signs like darkened skin in the neck folds, belly fat or sleepiness after meals. These signs are not a diagnosis; a doctor makes the diagnosis through an exam and tests. The good news is that moderate weight loss, physical activity, fiber-rich food and enough sleep can improve how sensitive your body is to insulin.

This article is for education. It doesn't replace a visit with your own doctor or their diagnosis.

What does insulin do, and what is resistance?

After you eat, especially starchy and sweet foods like rice, bread or dates, blood sugar rises. The pancreas releases insulin, which works like a key: it opens the doors of muscle, liver and fat cells so sugar can get in to be used or stored.

In insulin resistance, those locks have become a bit stiff. The key still works, but the body needs more keys to open the same doors. So the level of insulin in the blood goes up. As long as the pancreas can handle the extra load, blood sugar may stay normal and a sugar test may show nothing. But if this strain continues for years, blood sugar may slowly begin to rise too.

Factors that make insulin resistance more likely:

• Extra weight, especially fat around the belly
• Low activity and little muscle
• A family history of type 2 diabetes
• PCOS
• A history of gestational diabetes
• Chronic lack of sleep and some medications

Common signs

The most important point first: many people with insulin resistance have no obvious signs. And the reverse is true too: having one of the signs below doesn't mean you definitely have insulin resistance. They are only clues that are worth mentioning to your doctor.

Acanthosis nigricans

Dark, velvety skin in body folds, such as the back and sides of the neck, the armpits or the groin, is called acanthosis nigricans. It is a well-known skin sign of high insulin. Many people think it is "dirt" that will come off with a scrubbing mitt (kiseh), but it doesn't. If you notice a change like this in your skin, show it to your doctor.

Belly fat

Fat that collects around the belly and between the internal organs is more closely tied to insulin resistance than fat on the thighs and hips. That's why your waist measurement is sometimes more telling than your weight itself. With the calculator you can see your BMI, but measure your waist separately too.

Sleepiness and cravings after eating

Some people say that after a rice-heavy lunch they can't keep their eyes open, or that an hour or two after eating they crave sweets and bread again. Many people know this feeling, and it can go along with insulin resistance, but it has other causes too: lack of sleep, a large portion, dehydration or even habit. So don't jump to a conclusion from these feelings.

Other signs

• Small skin tags on the neck and armpits
• In women, irregular periods and other signs of PCOS
• High blood pressure or abnormal blood fats, especially high triglycerides and low HDL

Which tests might a doctor order?

There is no single simple, standard test for insulin resistance that is used in the clinic. A doctor is usually more interested in where your blood sugar stands and how high your risk of prediabetes and diabetes is. The choice of test is up to them, but these are the most common:

Common tests related to sugar and insulin

Test	What it shows	Note
Fasting blood sugar (FBS)	Blood sugar after about 8 hours without food	Simple and cheap, but may miss the early stages
Hemoglobin A1c	Average blood sugar over the past two to three months	No fasting needed; anemia and some blood conditions affect it
Oral glucose tolerance test (OGTT)	How the body handles a standard sugary drink over two hours	More sensitive in PCOS, and the 2023 guideline prefers it
Fasting insulin and HOMA-IR	An estimate of insulin level and resistance to it	No single standard and varies between labs; not recommended for routine diagnosis
Blood fats	Triglycerides, HDL and LDL	High triglycerides and low HDL go along with insulin resistance

About fasting insulin and HOMA-IR

You may have seen people online urging everyone to get an "insulin test." The reality is that fasting insulin isn't measured the same way in different labs, and there is no agreed cutoff for "normal." The 2023 international PCOS guideline also states plainly that these tests are not suitable for routine diagnosis of insulin resistance in clinical practice. So if your doctor didn't ask for this test, that doesn't mean they were careless. And if you already have your own HOMA-IR number, leave the interpretation to your doctor.

The link to prediabetes, type 2 diabetes and PCOS

You can think of insulin resistance as an earlier stage. When the pancreas can no longer keep up with the body's need for insulin, blood sugar slowly climbs:

1. Insulin resistance with normal sugar: insulin is high, but sugar is still in the normal range.
2. Prediabetes: fasting sugar, A1c or the OGTT result is above normal, but not yet at the diabetes level.
3. Type 2 diabetes: blood sugar has reached the diagnostic level for diabetes and needs regular medical care.

This path is not fixed or one-way. The large US Diabetes Prevention Program (DPP) study showed that in people with prediabetes, a lifestyle change aimed at losing about 7 percent of body weight and doing 150 minutes of activity a week substantially reduced the risk of developing type 2 diabetes.

In PCOS, insulin resistance is very common, even in people at a typical weight. High insulin can push the ovaries to make more "male" hormones and make some symptoms worse. That is why checking blood sugar from time to time is recommended in PCOS. If you'd like to know more, read the PCOS page and the article What is PCOS, and where does food fit in?.

Signs are only clues, and a doctor interprets the tests. But the things that improve insulin sensitivity are good for everyone, and you don't have to wait for a diagnosis.

What helps?

Moderate weight loss

If you carry extra weight, losing 5 to 10 percent of your body weight can improve insulin sensitivity and markers like sugar and triglycerides. You don't need to reach an "ideal" weight; this much already makes a difference.

Physical activity, especially building muscle

Muscle is the body's biggest user of sugar. Every time your muscles work, they take up sugar even with less insulin.

• Brisk walking: the overall goal is 150 minutes a week. Even 10 to 15 minutes of walking after dinner helps smooth out blood sugar after the meal.
• Strength training: two sessions a week; chair squats, wall push-ups, or exercises with water bottles or a resistance band.
• Sit less: every hour or two, stand up and walk for a few minutes.

Fiber and protein on your plate

Fiber slows sugar absorption and protein keeps you full longer. Legumes (lentil soup, bean stew, ash with more legumes and fewer noodles), fresh herbs and raw greens (sabzi khordan), salad, whole-grain bread such as sangak (whole-wheat flatbread), and whole fruit instead of juice are all good options. We cover both in Protein and fiber.

The order you eat in

Some studies have shown that eating vegetables and protein before carbohydrates makes the blood sugar rise after a meal gentler. That means salad and yogurt first, then the stew, and rice last. A simple trick that costs nothing.

Sleep and stress

Even a few nights of short sleep can temporarily lower insulin sensitivity. Adults need at least 7 hours of sleep. Heavy snoring and daytime sleepiness may also be signs of sleep apnea, which is linked to insulin resistance and should be mentioned to your doctor.

Sweet drinks

Soda, packaged juice and tea with several sugar cubes send sugar into the blood very quickly and don't make you feel full. Cutting back gradually, for example from three cubes to one, is one of the easiest steps.

When should you see a doctor?

• If you notice darkening of the skin in the neck folds or armpits
• If you have a family history of diabetes, gestational diabetes or PCOS
• If you have a lot of thirst, frequent urination, unexplained weight loss or blurred vision; these can be signs of high blood sugar and you shouldn't wait
• If you take medication and want to start a strict diet or fasting

Decisions about medication, such as metformin, are for your doctor only. Don't take supplements advertised as a "treatment for insulin resistance" without checking with them first.

Summary

Insulin resistance is common, often silent, and its signs alone aren't enough for a diagnosis. Diagnosis comes from a doctor and tests, and fasting insulin or HOMA-IR is usually not the best route. But the things that help are clear and within reach: moderate weight loss, movement and muscle building, fiber and protein on your plate, the right eating order and enough sleep.

If you'd like to see these in the form of a real plan, at Rejimist a doctor writes your personal diet from your questionnaire and stays with you through a short daily check-in by text message. Begin at start your diet.

Sources

• American Diabetes Association. Standards of Care in Diabetes — 2024: Classification and Diagnosis of Diabetes. Diabetes Care, 2024.
• Knowler WC, et al. Reduction in the incidence of type 2 diabetes with lifestyle intervention or metformin. New England Journal of Medicine, 2002.
• Teede HJ, et al. Recommendations from the 2023 International Evidence-based Guideline for the Assessment and Management of Polycystic Ovary Syndrome. Journal of Clinical Endocrinology & Metabolism, 2023.
• Shukla AP, et al. Food order has a significant impact on postprandial glucose and insulin levels. Diabetes Care, 2015.
• World Health Organization (WHO). Guidelines on Physical Activity and Sedentary Behaviour, 2020.
• Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. The Lancet, 1999.