Insulin resistance: definition, symptoms and natural treatments

Insulin resistance: definition

Insulin resistance is when the body’s cells stop responding properly to insulin (1).

Secreted by the pancreas, or more specifically beta cells of the islets of Langerhans, this hormone plays a major role in regulating glycaemia. Like a key turning in a lock, it binds to specific receptors on cell membranes, and directs fatty tissue, muscles and the liver to take in glucose (2). At the same time, it inhibits the depletion of glycogen, the body’s stored form of glucose.

In insulin resistance, cells gradually become less sensitive to the effects of insulin. At first, the pancreas redoubles its efforts to provide more insulin in order to ‘force’ sugar to penetrate cells: this is called compensatory hyperinsulinemia (3).

But over time, this boost in insulin production is no longer enough: the sugar remains in the blood, causing an increase in fasting blood sugar levels. When this reaches between 1.10 and 1.25, it is referred to as prediabetes (4) and once it exceeds this figure, the diagnosis moves towards type 2 diabetes (5).

Insulin resistance: symptoms

All the time it is not producing a marked rise in glycaemia, insulin resistance remains undetected and causes few symptoms.

However, the pancreatic overactivity it triggers often leads to metabolic abnormalities, such as hepatic steatosis (fatty liver) (the build-up of fat in the liver responsible for dyslipidaemia) (6).

Insulin resistance is also widely associated with metabolic syndrome (7). Affecting 40% of Americans over 50, this manifests in increased waist circumference and at least two of the following four problems: hypertension, excessively high blood triglycerides, low levels of ‘good’ HDL cholesterol, hyperglycaemia. Metabolic syndrome is a major risk factor for cardiovascular disease and diabetes, as well as kidney and liver disease.

Certain uncharacteristic blood markers sometimes suggest insulin resistance, such as an increase in gamma-glutamyl transferase, C-reactive protein (CRP) or ferritin (8).

Insulin resistance: causes

Insulin resistance and obesity

There is a strong interrelationship between insulin resistance and excess weight. Several studies have found increased production of adipokines by adipose cells (including TNF-α and IL-6) in obese subjects, which may interfere with insulin signalling and maintain low-grade inflammation, paving the way for insulin resistance (9). They have also noted abnormal infiltration of fatty tissue by macrophages.

Insulin resistance and PCOS

Polycystic ovary syndrome (PCOS) leads to androgen hypersecretion by the ovaries which encourages the development of adiposity. It thus predisposes to insulin resistance and metabolic syndrome, especially past the age of 50 (10).

Other causes of insulin resistance

Other known causes of insulin resistance include:

• an unhealthy lifestyle (physical inactivity, poor diet, smoking …) (11);
• gestational diabetes during pregnancy (12);
• certain viral infections such as HIV or hepatitis C (13);
• treatment with steroids (steroid-induced diabetes) (14);
• intense physical stress (a stay in intensive care for example) (15).

Insulin resistance and HOMA

Measured by a blood test, the HOMA (HOmeostasis Model Assessment) index can flag up insulin resistance even when blood sugar is normal. This tool is of real benefit in that it allows lifestyle/dietary measures or treatment to be introduced before the next stage of insulin resistant diabetes is reached.

The calculation is based on a mathematical model involving fasting blood glucose and insulin concentrations. A HOMA index of more than 2.4 is normally indicative of insulin resistance (16). The result must, however, be interpreted taking the patient’s clinical context into account.

Insulin resistance and weight loss

Insulin resistance can complicate efforts to lose weight. The sharp increase in insulin levels promotes the conversion of sugar into fat and its storage in adipose tissue – which further boosts insulin resistance, thus creating a vicious circle.

However, a reduction in fat mass in overweight individuals appears to stem the development of the disease by lowering lipotoxicity (17). Here are some tips that can help:

• review your eating habits, limiting foods that have a high glycaemic index (GI) (soft drinks, pastries, refined cereals…) and/or contain saturated fatty acids (butter, cooked meats, red meat …) (18);
• adopt the Mediterranean diet (high in fibre, vitamins and polyphenols) which has been shown to protect against insulin resistance and type 2 diabetes (19);
• boost your intake of oily fish and omega 3-rich plant oils (flax, rapeseed …) (20);
• engage in regular, moderate exercise (at least 150 minutes a week) (21).

Insulin resistance: treatments and natural aids

When lifestyle changes prove to be insufficient, therapeutic management is based on oral diabetes treatments.

Biguanides are a group of diabetes medications usually prescribed as a first-line treatment (22). They can be used with GLP1 analogues and/or SGLT2 inhibitors in combination therapy. Insulin injections are only used as a last resort. Only your GP or diabetes specialist can assess whether they should be used and judge how effective they are: medical supervision is therefore essential.

At the same time, certain dietary supplements can provide invaluable support in the context of insulin resistance. As they may interfere with your regular treatment, we’d advise you to consult a health professional before starting any supplementation.

Chromium helps maintain normal blood glucose and metabolism of macronutrients (protein, fats and carbohydrates). Several scientific papers have underlined its pivotal role in glucose homeostasis and its ability to optimise the effects of insulin (by modulating, in particular, the number and form of insulin receptors) (23). In addition, studies have observed chromium deficiency in type 2 diabetics (24).

Present in barberry, amongst others, berberine (highly concentrated in the supplement Berberine, a pure extract standardised to 97% berberine, the highest percentage on the market) is an alkaloid which has been studied to good effect in insulin-resistant subjects with metabolic syndrome. Research has focused, in particular, on measuring its impact on glycaemia and the inflammatory response (25).

A long time ingredient in the Asian pharmacopoeia, banaba (Lagestroemia speciosa) helps control blood glucose. Its main active ingredient is corosolic acid, sometimes referred to as ‘green insulin’ because of its effect on insulin sensitivity and secretion (the supplement Glucofit is standardised to 18% corosolic acid for maximum efficacy) (26).

Listed for more than 2000 years among Ayurvedic medicine’s blood sugar-lowering plants, the leaves of Gymnema sylvestre are able to support glucose metabolism because of their gymnemic acid content (Gymnema sylvestre is therefore standardised to 75% gymnemic acids). One study has reported their effects on individuals with impaired glucose tolerance, particularly in terms of blood glucose control, and insulin secretion and sensitivity (27).