Insulin resistance: symptoms, tests, and diet and exercise changes

You are not eating much, yet your waist keeps growing; after lunch you feel drowsy and soon hungry again; and your weight just will not move. Some people have a health check, find their blood sugar is “still in the normal range”, and are still told to watch out for “insulin resistance”. What exactly is insulin resistance, and does it mean diabetes is on the way?

Insulin resistance is one of the early signals of a metabolic problem. It usually causes no obvious symptoms and often appears together with more abdominal fat, low activity, poor sleep and stress, polycystic ovary syndrome or fatty liver. It is not the same as diabetes, but it deserves attention. Whether you truly have it, and which tests you need, should be assessed in person by a doctor according to your situation.

Key points: Insulin resistance means the body’s cells respond less well to insulin, so the pancreas has to release more insulin to keep blood sugar steady. It often has no obvious symptoms early on, and may be linked to more abdominal fat, difficulty managing weight, drowsiness after meals, frequent hunger, or darkened skin on the neck and underarms; it is also common with polycystic ovary syndrome and fatty liver. Whether you have it needs to be assessed by a doctor using your history and blood tests. Diet, activity, sleep and weight management are the foundation of care, not any single food or supplement. If your blood sugar is already high or you have related symptoms, please have a doctor assess you in person.

What is insulin resistance? Why does it affect blood sugar and weight?

Insulin is a hormone made by the pancreas. It works like a key, helping glucose in the blood enter the cells of muscle, fat and liver to be used as energy. Insulin resistance means these cells respond less well to insulin, so the same amount of insulin opens the door less efficiently.

To keep blood sugar steady, the pancreas may release more insulin to “compensate”. For a while blood sugar may still look normal even though insulin levels in the blood are already high; if compensation cannot keep up, blood sugar gradually rises, moving into prediabetes and possibly type 2 diabetes.

Higher insulin levels may also affect how fat is stored and how appetite is regulated, so insulin resistance and weight gain, especially abdominal fat, often influence each other in a loop. In other words, weight and insulin resistance are not a one-way cause and effect but a metabolic state in which each affects the other.

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What are the symptoms and warning signs of insulin resistance?

Insulin resistance usually has no specific symptoms in its early stage, and many people only notice it during a health check or when they see a doctor about weight, skin or menstrual problems. The clues below may be related, but having them does not mean you have insulin resistance, and they cannot be used for self-diagnosis:

Signs related to weight, appetite and energy

A growing waist and belly fat that is especially hard to lose; drowsiness after meals; feeling hungry again soon after eating, with cravings for sweets or starchy food; and weight loss that keeps stalling. These can also come from poor sleep, stress, diet or other illnesses, so they need to be considered together.

Signs related to skin and hormones

Grey-brown, thick, velvety patches in skin folds such as the back of the neck and underarms may be acanthosis nigricans, one of the metabolism-related skin signals commonly seen in dermatology. Women who also have irregular periods, more acne or excess hair should also consider whether polycystic ovary syndrome is involved.

Signs when blood sugar is already high

When blood sugar is clearly high, there may be thirst, drinking a lot, frequent urination, tiredness and blurred vision, similar to diabetes. If you have these, please see a doctor soon for blood tests rather than trying to manage on your own with diet or supplements.

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What causes insulin resistance, and who is at higher risk?

The causes of insulin resistance are not a single thing. It is thought to relate to genetics, body fat (especially abdominal and visceral fat), activity level, sleep and stress, and hormone status. Common related factors and higher-risk groups include:

• Abdominal obesity or weight gain: when the waist is large and visceral fat is higher, insulin often works less well.
• Low activity and prolonged sitting: when muscles are used less, their use of glucose also falls.
• Family history of diabetes: people with a first-degree relative with diabetes have a higher risk.
• Polycystic ovary syndrome: many patients also have insulin resistance, and may have irregular periods, acne and excess hair.
• Fatty liver and metabolic syndrome: when several measures of blood pressure, blood fats, blood sugar and waist size are off, insulin resistance often coexists.
• History of gestational diabetes: regular blood sugar follow-up is still advised after delivery.
• Poor sleep, sleep apnea and long-term stress: these may affect blood sugar and appetite regulation.
• Some medicines or increasing age: a few medicines may affect blood sugar; if you take medicines, do not stop them on your own and talk with your doctor.

Fatty liver is closely linked to insulin resistance; to understand how fat builds up in the liver, see causes of fatty liver, and to understand how abnormal blood sugar is classified, see the types of diabetes.

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How is insulin resistance tested? How should the numbers be read?

There is no single, universal “one test settles it” standard for insulin resistance. In practice, a doctor usually first asks about your history, family history, changes in weight and waist size, menstruation and sleep, and then arranges blood tests and a physical assessment according to your situation.

Common items include fasting blood sugar, glycated hemoglobin, blood fats and liver function, plus waist size and blood pressure; when needed, the doctor may consider fasting insulin, an oral glucose tolerance test (OGTT), or the HOMA-IR index calculated from fasting glucose and fasting insulin. Reference cut-offs for HOMA-IR differ between facilities and populations, so no single number should be read alone; the doctor interprets it together with other information.

According to Taiwan’s Health Promotion Administration and Ministry of Health and Welfare, a fasting blood sugar of 100 to 125 mg/dL, or a glycated hemoglobin of 5.7% to 6.4%, counts as prediabetes; and if blood sugar is abnormal together with any two of abdominal obesity, raised blood pressure, raised fasting triglycerides and low HDL cholesterol, the criteria for metabolic syndrome are met. In Taiwan, people aged 30 and over can also use the free adult preventive health service to learn their own blood sugar, blood pressure and blood fat results.

Whether you need extra insulin-related tests and how often to follow up should be decided by your doctor based on your age, weight, family history and other results. Buying a home test kit and drawing a conclusion from a single value is not recommended.

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How do insulin resistance, prediabetes, metabolic syndrome and diabetes differ?

These terms are often mentioned together but mean different things. The table below summarizes common differences for understanding only; the actual diagnosis and classification must be made by a doctor from test results.

Feature	Insulin resistance	Prediabetes	Metabolic syndrome	Diabetes
Meaning	A state in which cells respond less well to insulin; not a stand-alone diagnosis	Blood sugar higher than normal but not yet at the diagnostic level for diabetes	A cluster of abnormal measures such as waist size, blood pressure, blood sugar and blood fats	A chronic condition in which blood sugar reaches the diagnostic level
Blood sugar	May still be normal, or may already be raised	Fasting glucose or glycated hemoglobin falls in the prediabetes range	Blood sugar may be raised, but it is not the only criterion on its own	Fasting glucose, glycated hemoglobin or other tests reach the diagnostic level
Common symptoms	Usually no obvious symptoms	Usually no obvious symptoms	Often no symptoms; a larger waist is most noticeable	May include thirst, frequent urination, tiredness and weight changes
How it is found	Assessed by a doctor from history, blood tests and other information	Blood sugar or glycated hemoglobin tests	Judged from waist size, blood pressure and blood test values	Diagnosed by a doctor from blood sugar-related tests
Management direction	Lifestyle, weight management and follow-up, assessed by a doctor	Lifestyle changes and regular follow-up, assessed by a doctor	Overall assessment and follow-up for each abnormal measure	Treatment and long-term follow-up planned by a doctor

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How are insulin resistance and weight management related?

When body fat, especially abdominal fat, rises, insulin often works less well, and insulin resistance can in turn make weight harder to lose, so the two may form a loop. For people with insulin resistance or prediabetes, managing weight and waist size is therefore usually one of the points a doctor assesses.

That does not mean losing weight by extreme methods. Crash dieting, cutting out starchy food for long periods or overexercising may cause muscle loss, fatigue and emotional stress, and are hard to keep up. A more workable direction is to adjust what you eat and how active you are to fit your lifestyle, with help from a doctor or dietitian, while preserving muscle.

To learn more about balancing body fat and muscle, see how to lose fat without losing muscle; to understand roughly how much energy you need each day, see the explanation of basal metabolic rate; and if your weight stalls during weight loss, see how to break a weight-loss plateau.

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How is insulin resistance managed? Can it improve?

The core of managing insulin resistance is to improve the body’s sensitivity to insulin while following blood sugar, blood fats, liver function and blood pressure. Many people may see related measures improve gradually through lifestyle changes and weight management, but the degree and speed vary from person to person and may fluctuate, so regular follow-up is needed. Common approaches include:

• Adjusting what you eat: cut down on sugary drinks, desserts and refined starch, add vegetables, protein and dietary fiber, and choose relatively unrefined whole grains.
• Regular activity: combine aerobic activity with resistance training, which helps muscle use glucose. If you have existing illnesses or discomfort, talk with your doctor first.
• Sleep and stress management: poor sleep and long-term stress may affect appetite and blood sugar regulation.
• Weight and waist management: the doctor may help set reasonable, sustainable goals according to your situation.
• Dealing with related conditions: for example polycystic ovary syndrome, fatty liver, blood pressure and blood fat problems, which may need assessment by other specialties as well.
• Medicine assessment when needed: after assessment, some people may be offered medicines related to blood sugar or weight management; the indications, contraindications, side effects and follow-up should all be explained by the doctor according to the individual.
• Regular follow-up: return visits, blood tests and records of weight and waist size as your doctor arranges are how you know whether the changes are working.

To learn about the classes and risks of weight-management medicines, see the explanation of GLP-1 class medicines; whether they suit you must be assessed in person by a doctor, and you can also first learn about how the weight-management clinic assesses patients.

Whichever approach is used, buying or using supplements or folk remedies of unknown origin on your own is not recommended, nor is stopping medicines you are already taking just to get quick changes.

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Diet and exercise in daily life: 8 key points for insulin resistance

These are general lifestyle directions that can be adjusted to your condition, work pattern and eating habits; if you already have diabetes or kidney disease or use blood sugar-lowering medicines, talk with your doctor before making changes.

• Vegetables at every meal: eat vegetables and protein before the starchy part of the meal, and keep a good share of vegetables on the plate.
• Choose less processed staples: replace part of the white rice, white noodles and bread with whole grains, keeping portions moderate.
• Cut down on sugary drinks: bubble tea, sweetened coffee and juice are often hidden sources of sugar and can be reduced step by step.
• Enough protein in moderation: beans, fish, eggs and meat help with fullness and with keeping muscle.
• Light activity after meals: a walk or some housework after eating helps build up daily activity.
• Regular weekly exercise: arrange aerobic and resistance training to suit your condition, starting at an intensity you can keep up.
• Keep a regular sleep schedule: keep routines regular where possible and talk with your doctor if sleep is a problem.
• Record and follow up: keep a record of weight, waist size and meals for your doctor to review at visits.

The key is what you can keep up over the long term, not extreme change in a short time. If you feel dizzy, have palpitations or break out in a cold sweat, pause and see a doctor.

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Common myths about insulin resistance

Myth 1: Only overweight people have insulin resistance?

Not necessarily. Weight and abdominal fat gain are common related factors, but people who are not overweight may also have it because of genetics, low activity, low muscle mass, polycystic ovary syndrome or other causes, so body shape alone cannot be used to judge.

Myth 2: Having insulin resistance means you already have diabetes?

No. Insulin resistance is a state in which the body responds less well, and blood sugar may still be normal; diabetes is diagnosed when blood sugar-related tests reach the diagnostic level. The two are related but not equal, and the actual judgment needs a doctor’s assessment.

Myth 3: Staying off starchy food for long will fix insulin resistance?

Extreme avoidance is not recommended. Staying off staple foods for long may cause fatigue and muscle loss and is hard to keep up, and weight may rebound afterwards. A more workable approach is to adjust the type and portion of starch, together with vegetables and protein, with advice from a doctor or dietitian.

Myth 4: Supplements or fasting can quickly improve insulin resistance?

At present no single food, supplement or short-term method can replace overall lifestyle management. Fasting and special diets are not suitable for everyone, especially people with diabetes, those using blood sugar-lowering medicines, pregnant women or people with eating difficulties, who should talk with a doctor first and not try them on their own.

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When should you see a doctor?

If your waist is growing, your weight is hard to manage, diabetes runs in your family, you have polycystic ovary syndrome, or the skin of your neck or underarms has darkened, consider arranging a full health and metabolic assessment. See a doctor sooner if any of the following apply:

• A health check shows high fasting blood sugar or high glycated hemoglobin, or you have been told you have prediabetes.
• You have thirst, frequent urination, noticeable weight change without trying, blurred vision or tiredness.
• Your waist has grown noticeably and blood pressure, blood fats or liver function are also abnormal.
• As a woman you have irregular periods, marked acne or excess hair and want to understand the link with hormones and metabolism.
• The skin of the neck or underarms has darkened and thickened, or the area is spreading quickly.
• You have worked on diet and exercise, but weight and waist size have not changed for a long time.
• A child or teenager is gaining weight quickly and also has darkened skin or other metabolic warning signs.

To have your weight and metabolism assessed, visit the Ruian Clinic weight-management clinic for an in-person assessment by a doctor, and read more metabolism and weight topics in the health library.

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Health Education References

• Ministry of Health and Welfare (Taiwan): regular checks and healthy habits, 4 ways to look after blood sugar
• Taiwan Society of Laboratory Medicine: insulin resistance and its assessment
• National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK): Insulin Resistance & Prediabetes

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This article provides disease health education and is not pharmaceutical advertising. It does not promote or sell specific medications and cannot replace a doctor’s examination; the actual diagnosis, tests and treatment must be assessed in person by a doctor according to your individual situation.

Weight-management medical team