CARBOHYDRATE METABOLISM

WHAT IS INSULIN RESISTANCE

ინსულინრეზისტენტობა

Insulin is a very important hormone which is secreted by pancreas. One of its main role is to help cells to use glucose as an energy source.

See more about insulin action: INSULIN

Insulin resistance means that cells ignore insulin's action.
The body turns on compensative mechanisms in order to give cells energy and to avoid accumulation of unused sugar in the blood. This mechanism means to intensify insulin release by pancreas to overlay cell's insensitivity. But another problems begin from here due to hyperinsulinemia.

Elevated insulin level can cause conditions, such as:

  • Obesity
  • disorders of lipid metabolism
  • atherosclerosis
  • elevated blood pressure
  • polycystic ovarian syndrome
  • infertility

This list may continue. If genetic susceptibility and certain environmental factors are present, hard work can cause exhaustion of pancreas and decrease insulin release. This leads rising blood sugar level and developing prediabetes and type 2 diabetes.

Prediabetes includes the diagnosis of decreased glucose tolerance and/or impaired fasting glucose. During these conditions blood glucose level is high than normal but still not in diabetes range.

The main risk factors for developing insulin resistance are:

  • being overweight or obesity, especially when fat is mostly accumulated in belly area
  • sedentary lifestyle
  • unhealthy eating habit
  • sleep deprivation
  • using tobacco

Due to modern lifestyle the incidence of metabolic diseases including insulin resistance is markedly increased already from younger age and among children too.

Insulin resistance have no symptoms itself, but over time it causes a serious complications, such as:

  • infertility
  • cardiovascular diseases
  • type 2 diabetes

The treatment of insulin resistance must include neutralization of it's risk factors. So the plan is:

  • healthy and balanced diet and decrease body mass
  • increase physical activity
  • adjust sleep patterns
  • stop smoking

Insulin resistance and obesity

There is such a tight connection between insulin resistance and obesity, that it's hard to tell which of them begins first.

It's established that increasing fat tissue volume can cause developing or worsening insulin resistance. And the processes that begin due to insulin resistance including hyperinsulinemia are provocative for developing obesity.

The distribution of extra fat in the body is very important factor and elevated Body Mass Index alone isn't a good predictor of insulin resistance. The main criteria is presence of extra belly fat, because this type of fat is more metabolic active than subcutaneous peripheral fat. Because of this the waist circumference is the main criteria for insulin resistance risk assessment. The normal waist circumference is less then 102 sm for man and less then 88 sm for woman.

So the normal BMI doesn't exclude presence of insulin resistance.

The main part of obesity treatment must be detecting insulin resistance, because it's very difficult to loose weight when hyperinsulinemia is present.

The diagnostic test for insulin resistance

Insulin sensitivity can be estimated by the Homeostasis Model Assessment or HOMA index. For calculation of HOMA the following is needed:

  1. Fasting levels of insulin and glucose must be determined in venous sample;
  2. These results are used in the formula: HOMA IR=( glucose (mmol/L ) X insulin (mU/L)) / 22.5 X insulin - (mU/L)) / 22,5

The normal range for HOMA IR is between 0.5 - 1.4.

  • HOMA IR 1,4-1,9 – points to mild changes
  • HOMA IR 2.0-2.9 – points to early insulin resistance
  • HOMA IR more than 3.0 - is a sign of marked insulin resistance.

Glucose and insulin tests for HOMA index calculation is performed in the morning in a fasting state - minimum 8 hours after the last meal.

Written by: Elga Giorgadze, MD