Understanding impaired glucose tolerance and insulin resistance

How these changes in glucose and insulin levels can affect your health, when you have type 2 diabetes

People who develop type 2 diabetes usually experience two preliminary stages: insulin resistance and impaired glucose tolerance.

What Is Insulin Resistance?

Insulin is a hormone made by the body which lets you use sugar (glucose) from carbohydrates in the food you eat for energy. If your body is insulin resistant, your pancreas will have to pump more insulin in order to bring down your blood sugar levels. Eventually though your pancreas may be unable to cope.

The human body is not meant to have high levels of circulating insulin. Some of the problems that occur when a person has high circulating levels of insulin and insulin resistance include:

  • Triglyceride levels increase. Higher-than-normal triglycerides, a type of blood fat or blood lipid, may increase a person's risk of developing atherosclerosis or artery-clogging heart disease.
  • HDL cholesterol drops. This so-called good cholesterol fraction fall is bad news for your body. Extensive research reveals that people with lower HDL cholesterol levels have an increased risk for atherosclerosis.
  • The body retains sodium, which can lead to fluid retention. Among other things, fluid retention can raise blood pressure. Blood pressure rises, causing stress on the cardiovascular system. Blood-clotting mechanisms become overactive.
  • Excess insulin levels cause the body to produce fibrinogen, one of the body's blood-clotting mechanisms, in too-high levels. Among other problems, high fibrinogen levels can cause the formation of tiny blood clots that can clog arteries and contribute to atherosclerosis.
  • LDL cholesterol changes. This so-called bad cholesterol fraction becomes abnormally dense. Dense LDL cholesterol also increases the risk for atherosclerosis.
  • Impaired glucose tolerance. The majority of people who have insulin resistance often develop impaired glucose tolerance, which takes them one step closer to type 2 diabetes. Over time, a person with insulin resistance produces more insulin to move the same amount glucose into the cells, where it is needed for energy. In many people, this ability to compensate eventually breaks down. When this happens, blood sugar level starts to climb, despite the high levels of insulin.

What Is Impaired Glucose Tolerance?

Impaired glucose tolerance is also commonly referred to as pre-diabetes, as it indicates that the patient has a higher than normal glucose levels but not high enough to be diagnosed as diabetes1. These raised glucose levels put the patient at a greater risk of developing diabetes.

Symptoms can be mild, such as slightly increased thirst or more frequent urination, or not present at all. However, higher than normal blood sugar levels can begin to cause damage in many organs, such as the kidneys, eyes, and blood vessels.

1Health Promotion Board of Singapore. Retrieved on Dec 31, 2015 from: http://www.hpb.gov.sg/HOPPortal/health-article/HPB-038016