HOMA-IR: A Test of Insulin Resistance + Ways to Decrease It

HOMA-IR tells you how much insulin your body needs to keep your blood sugar levels in check. This test was designed to measure insulin resistance, an early stage of type 2 diabetes that increases your risk of many chronic diseases. Read on to learn about what causes high HOMA-IR and how to improve insulin resistance with lifestyle and dietary modifications.

Insulin Resistance

Your blood sugar (glucose) levels may be normal, but if your insulin levels are high, your body is likely struggling to maintain blood sugar levels in balance.

When cells no longer respond to insulin, your body needs to release more insulin to control blood sugar levels. This condition is called “insulin resistance” [1, 2].

Insulin is the hormone pancreas releases after you eat and it signals an abundance of energy in the body. Insulin lowers blood sugar by increasing its uptake and storage in tissues. Muscles take up 60-70%, the liver about 30%, and fat tissue around 10% of sugar from the blood [3, 1, 2].

What is HOMA-IR?

HOMA-IR (Homeostatic Model Assessment of Insulin Resistance) tells you and your doctor how much insulin your pancreas needs to make to control your blood sugar levels [4].

HOMA-IR was developed in the 80s and is an indirect measure: it is calculated from your fasting glucose and fasting insulin levels. While it might not be the best model overall, it’s still the most widely used model in clinical research [5, 6, 7].

Other recently-developed indirect measures of insulin resistance include HOMA2, QUICKI, and the triglyceride/HDL ratio [4].

Measuring insulin resistance directly is impractical, complicated, and doctors rarely use it (the method is called hyperinsulinemic-euglycemic glucose clamp) [1, 3].

Normal Range

Different studies provide slightly different ranges for HOMA-IR. But they all agree that the higher your HOMA-IR gets, the more insulin resistant you are.

Generally, you have optimal insulin sensitivity if your HOMA-IR is less than 1. Levels above 1.9 signal early insulin resistance, while levels above 2.9 signal significant insulin resistance.

High HOMA-IR

If your HOMA-IR is high, your body is using more insulin than normal to keep your blood sugar in balance. The higher the number, the more resistant you are to insulin. Your doctor will interpret your HOMA-IR in conjunction with your signs and symptoms, medical history, and other test results.

Insulin resistance is one of the symptoms of metabolic syndrome and an early stage in developing type 2 diabetes.

Causes

In most “healthy” people, insulin resistance is mainly caused by two factors: overeating and lack of physical activity. Eating too much and being inactive can cause a buildup of fat in the liver and muscles, which makes these tissues less responsive to insulin [8].

Other causes of insulin resistance include stress, pregnancy, and various disorders and diseases. Causes listed below have been associated with higher insulin resistance levels. Work with your doctor or another health care professional to get an accurate diagnosis.

1) Overeating/Nutrient Excess

Chronic excessive overeating increases oxidative stress and low-grade inflammation in the body [9, 10, 11].

Studies have shown that an excess of glucose and protein lead to insulin resistance in the muscles, while saturated fat increases insulin resistance in the liver [12, 13].

When 6 healthy men were fed a diet of over 6,000 kcal/day, they gained 3.5 kg on average in a week and developed insulin resistance after only 2 – 3 days [14].

In another study, palm oil, which is high in saturated fat, increased insulin resistance by 25% in 14 people (15% in the liver and 34% in fat tissue) [13].

2) Obesity

Obesity is the most common cause of insulin resistance and type 2 diabetes. Simply by being overweight (BMI >25), you have a 3 times higher risk of developing type 2 diabetes [15, 16].

In two studies with over 3k children and 137 adolescents, being overweight or obese was persistently associated with higher HOMA-IR [17, 18].

However, not all fat tissue is created equal. While the amount of fat in the body does correlate with insulin resistance, how that fat is distributed is more important.

Fat around internal organs, also known as belly fat or visceral fat, increases your risk of insulin resistance and type 2 diabetes. Fat underneath the skin, known as subcutaneous fat, decreases the risk [2, 15].

3) Sedentary Lifestyle/ Physical Inactivity

Early insulin resistance occurs rapidly after short-term physical inactivity (1-7 days). Inactive muscles are probably the primary cause, but the exact mechanism is still unclear [19].

In a study of over 3k children, lower physical activity was associated with higher HOMA-IR [17].

Sitting for long periods of time without getting up was linked to higher insulin resistance in a review of 3 studies with a total of 62 people. The higher the insulin resistance, the more the people benefit from interrupting long sitting periods with regular, brief activity breaks [20].

4) Stress

Activation of the stress response, also known as the hypothalamo-pituitary adrenal (HPA) axis, increases cortisol, which impairs insulin function [3].

In 766 workers, job-related stress was significantly associated with insulin resistance. What’s more, those with higher cortisol levels had higher HOMA-IR [21].

Work-related stress was associated with increased HOMA-IR in another study of 366 patients with polycystic ovary syndrome (PCOS) and 325 controls. Additionally, higher HOMA-IR increased the risk of PCOS [22].

Research has shown that stress also causes insulin resistance in severe illness [3].

5) Not Enough or Too Much Sleep

Most people need 7-8 h of sleep per night for optimal health. Getting more or less than you need may be detrimental. For example, both shorter and longer sleep duration were associated with higher insulin levels in a study with over 2.8k people [23, 24].

In 245 high school students, those who slept less during the night had higher HOMA-IR [25].

In the short term, lack of sleep increases blood sugar levels by activating the stress HPA axis and increasing cortisol. In the long term, chronic sleep deprivation triggers insulin resistance [3, 26, 23, 27].

In 5.8k people, excessive daytime napping was linked with higher HOMA-IR [28].

6) Sleep Apnea

Researchers found that people with obstructive sleep apnea are at an increased risk of insulin resistance and diabetes [29, 30].

According to a meta-analysis of 16 studies, people with sleep apnea have higher HOMA-IR than healthy people [31].

In sleep apnea, overactivation of the HPA axis impairs insulin function. Lack of oxygen may also contribute by increasing inflammation, especially in fat tissue [3, 30].

7) Starvation

Insulin resistance develops within 2-3 days of starvation [32, 33, 34].

That is why some initially obese individuals can develop diabetes on crash diets when they adopt strenuous weight-reduction regimens [35].

8) Muscle Damage Due To Exercise

In general, exercise beneficially affects insulin resistance and HOMA-IR [36, 37].

But this isn’t the case if you exercise too much or incorrectly, which can both cause muscle damage and inflammation [38].

Muscle damage is typical after eccentric repetitive activity such as running or walking downhill. Your muscles are suddenly forced to stay contracted over an extended period of time [39].

When 12 healthy women ran downhill for 45 minutes, their insulin and HOMA-IR levels went up and stayed high throughout the recovery period of 1-4 days [40].

This doesn’t mean you shouldn’t do eccentric exercise, but keep in mind how it affects your insulin production and avoid it before testing.

9) Hypothyroidism and Hyperthyroidism

Thyroid hormones are important for overall metabolism, including blood sugar control.

Both high (hyperthyroidism) and low (hypothyroidism) thyroid hormone levels disrupt insulin function. In hyperthyroidism, insulin resistance in the liver disrupts glucose balance; in hypothyroidism, the culprit is insulin resistance in the muscles and fat tissue [41, 42, 43].

A study of 60 people revealed that even those with mild hypothyroidism (TSH ≤ 9.9 µIU/ml) can have higher insulin levels and HOMA-IR [44].

10) Pregnancy

Insulin resistance increases during the course of a normal pregnancy, reaching its peak in the third trimester [3].

In excess, insulin resistance in pregnancy can lead to gestational diabetes [3].

In addition, insulin resistance can spike in subsequent pregnancies. Insulin levels and HOMA-IR increased with multiple pregnancies in a study that compared 100 women in their first pregnancy and 100 women with multiple pregnancies [45].

11) Pollution

Compounds called persistent organic pollutants (POPs) can contribute to the development of insulin resistance and type 2 diabetes [46].

POPs can be found in pesticides, insecticides, fungicides, flame retardants, paint, plastics (PCBs), etc.

Studies have found that workers who are regularly exposed to these chemicals are more likely to develop diabetes [47, 48, 49].

In a larger study of 2k adults, diabetes was strongly associated with higher blood levels of six different POPs [50].

12) Genetics

Although insulin resistance is mainly an acquired condition, your genes can make you more susceptible [1, 30].

How do we know this? Scientists found that people who develop insulin resistance often have a history of type 2 diabetes in their families [30].

In addition, certain populations are more at risk than others. Studies have found that in the US, black Americans and Pima Indians have a higher risk of insulin resistance than whites. In Asia, Indians and the Chinese are at high risk of insulin resistance [30].

13) Aging

Insulin resistance is more common in seniors [30, 51].

This is, in part, because people get more belly fat and become less active as they age. Additionally, your energy requirements decrease as you age, making overeating more likely. But additional factors, such as increased oxidative stress and impaired mitochondrial function, may also play a role [30, 8].

14) Diseases of the Pancreas

Insulin levels can increase in people with an enlarged pancreas (pancreatic beta cell hyperplasia) [52, 53].

In addition, insulin levels increase in insulinomas, which are mostly benign pancreatic tumors [54, 55].

15) Hormonal Disorders

Hormonal disorders can disrupt normal glucose metabolism.

For example, insulin levels increase in acromegaly, a disease in which there is an overproduction of growth hormone [56].

Insulin also increases in Cushing’s syndrome, due to the excess of cortisol [57].

16) Other (Rare Disorders)

Insulin resistance is a major feature of some rare inherited or acquired disorders, such as [3]:

• Down’s Syndrome
• Turner’s Syndrome
• Klinefelter’s Syndrome
• Thalassaemia
• Hemochromatosis
• Lipodystrophy
• Progeria
• Huntington’s
• Myotonic dystrophy
• Friedrich’s ataxia
• Laurence-Moon-Biedel syndrome
• Glycogen storage diseases type I & III
• Mitochondrial disorders

Health Effects

Scientists generally agree that insulin resistance can increase the risk of developing [1, 3]:

• Diabetes
• Metabolic syndrome (including high blood pressure and high cholesterol)
• Heart disease
• Liver disease
• Polycystic ovary syndrome (PCOS)

1) Diabetes

The major consequence of insulin resistance is eventually developing type 2 diabetes.

Insulin resistance precedes the development of diabetes by 10 to 15 years [1].

2) Metabolic Syndrome

Insulin resistance can precede a cluster of health problems called “The Insulin Resistance Syndrome” or “The Metabolic Syndrome” [58, 3, 30]. These include:

• High blood pressure
• High blood sugar
• Excess belly fat
• High bad cholesterol/low good cholesterol
• High triglycerides

In a study with over 2,300 people, those with higher insulin resistance at baseline had more than a 5 times greater risk of developing metabolic syndrome 5 years later [59].

In another study that monitored 3,400 people over 20 years, those with the highest insulin levels and HOMA-IR had a much greater risk of eventually developing high blood pressure [60].

3) Heart Disease

According to a meta-analysis of 9 studies with over 22,000 people, those with higher fasting insulin were at an increased risk of heart disease [61].

In addition, in a study that followed 2,500 people over 20 years, the highest HOMA-IR values were associated with an almost 70% higher risk of dying of heart disease compared to low HOMA-IR levels [62].

4) Fatty Liver

Insulin resistance in fat tissue and muscles causes more free fatty acids to be carried to the liver. The fatty acids trigger an over-production of triglycerides, which develops into fatty liver [3].

In fact, HOMA-IR has been studied as a screening test for diagnosing fatty liver disease [63, 64].

5) PCOS

Polycystic ovary syndrome (PCOS) is the most common hormone disorder of premenopausal women.

Insulin resistance can precede PCOS and contributes to its development by causing a disbalance in sex hormones [3].

6) Cancer

Insulin resistance has been implicated in the development of certain cancers, including colon, endometrial, thyroid, pancreatic, kidney, and breast cancer [3, 65].

The association is possibly due to a disbalance in sex hormones and IGF-1 levels [3].

More studies are needed to clarify the role insulin resistance plays in cancer.

7) Cognitive Decline

In 1,416 mid-life nurses, higher insulin levels were associated with a faster cognitive decline and worse verbal memory after 10+ years [66].

In a study of 351 people, higher HOMA-IR was related to subsequent poorer cognitive performance and greater cognitive decline [67].

Ways To Decrease HOMA-IR

The most important thing is to work with your doctor to find out what’s causing your high HOMA-IR and insulin resistance and to treat any underlying conditions.

The additional lifestyle changes listed below are other things you may want to discuss with your doctor. None of these strategies should ever be done in place of what your doctor recommends or prescribes!

In general, the best approach to decreasing insulin resistance is changing your lifestyle. The two most important steps you can take are [1, 8]:

• Improving your nutrition: reducing the amount of overall calories in meals, eating more fiber and less processed carbs
• Becoming more active: getting plenty of exercise and taking regular active breaks from prolonged sitting.

Dietary Changes

1) Fasting/Calorie Restriction

When it comes to insulin resistance, less is more. The best thing you can do for your HOMA-IR index is to eat less, i.e. consume fewer calories [68, 69, 70]!

While there is a belief that high sugar intake contributes to diabetes, studies now suggest that sugar may be bad only as it contributes to excessive energy intake in general [71].

If you are baffled or frustrated by the prospect of counting calories, don’t despair. Studies suggest that intermittent fasting and alternate-day fasting can also help decrease insulin resistance and are promising strategies for diabetes prevention [72, 73, 74].

2) Fruits and Vegetables

While the number of calories you consume is important, where those calories come from also matters.

The Mediterranean diet, rich in fruits and vegetables, olive oil, and nuts, has been repeatedly linked with improved insulin sensitivity and a lower risk of getting type 2 diabetes [75, 76, 77].

In 418 non-diabetic people, following the Mediterranean diet for 4 years lowered diabetes risk by 50%, compared to a low-fat diet [78].

In 72 diabetics, a vegetarian calorie-restricted diet improved insulin sensitivity better than the conventional omnivore version after 6 months [79].

Why are plant-based foods beneficial? Plants are usually high in fiber (covered below).

Studies have also found that protein, and especially branched-chain amino acids (BCAA), worsen insulin resistance [80].

A study in 15 postmenopausal women revealed that even partly replacing meat with soy in a moderately high-protein diet improved insulin sensitivity [81].

3) Fiber

Whether it’s whole grains, insoluble cereal fibers, resistant starch, or soluble fibers – studies generally agree that more fiber is good for your sugar balance [82, 83, 3, 84, 85, 86].

High intake of dietary fiber (>25 g/d in women and >38 g/d in men) has been consistently associated with a 20-30% reduced risk of developing type 2 diabetes [82, 85, 87].

In two studies with over 11k people in total, those with higher dietary fiber intake had lower HOMA-IR [88, 89].

In another study with almost 5.5k people, those who ate more whole grains had lower insulin resistance, less inflammation, and lower chances of getting diabetes [90].

Adding more fiber to your diet can improve your HOMA-IR pretty fast: 12 weeks of supplementation with soluble fiber was enough to effectively lower insulin resistance in a study with 120 overweight men [84].

Lifestyle Changes

4) Weight Loss

Calorie restriction works when it comes to insulin resistance because it helps you lose weight – especially belly fat.

In a study with 56 women, those who successfully lost weight had better insulin sensitivity than those who regained it. Weight loss itself was the strongest predictor of improved insulin sensitivity [91].

Researchers found that gastric bypass resolves type 2 diabetes in approximately 80% of patients [2]!

Weight loss doesn’t have to be radical to be effective. In 2 studies with 48 obese and 8 diabetic people, respectively, gradual loss of 5 – 8% body fat was enough to lower belly and liver fat as well as insulin resistance [92, 15].

5) Exercise

Physical activity does wonders for insulin levels and glucose control [17, 93, 94, 95, 96].

According to a meta-analysis of 11 studies with 846 diabetics, exercise was effective in decreasing insulin levels and lowering insulin resistance [97].

But is the type of physical activity important?

According to a study in 1229 people, leisure-time physical activity is beneficial for HOMA-IR, while occupational and household physical activities are not [98].

6) Sleep

Get enough good-quality sleep. This will help decrease insulin and blood sugar levels [25, 99].

7) De-Stress

Take time to deal with the stress in your life. Any activity that helps you unwind and decreases your cortisol levels will have a beneficial effect on your insulin levels – whether it’s a relaxation technique, meditation, yoga, exercise, a hobby, or simply having fun.

Studies show that relaxation techniques such as yoga and meditation have beneficial effects on insulin resistance [100, 101, 102].

8) Deal with Infections and Inflammation

If you are suffering from infections and/or inflammation, those may be contributing to your insulin resistance [103].

In a study of 811 people, those who had an H. pylori infection were more likely to have a high HOMA-IR index (> 2.5) [104].

In addition, in 370 patients, HOMA-IR decreased with successful eradication of H. pylori [105].

Another culprit that can increase your insulin resistance without you knowing it is gum inflammation (periodontitis). Proper dental hygiene and regular visits to the dentist are important for your overall metabolic health. Treating gum disease reduces insulin resistance in diabetics [106].

Supplements

Talk to your doctor about the following foods and supplements. Initial studies suggest they may help decrease insulin resistance:

• Alpha-lipoic acid [107]
• Chromium [108, 109]
• Cinnamon [110, 111]
• Cocoa/dark chocolate [112, 113]
• Fenugreek [114]
• Fiber, such as resistant starch [115]
• Flaxseed [116]
• Green tea [117, 118]
• Magnesium [119, 120, 121, 122]
• Nuts – including pistachios, walnuts, almonds, and hazelnuts [123, 124, 125]
• Vitamin D (if deficient) [126, 127, 128, 129]
• Zinc (if deficient) [130, 131, 132]