What is insulin resistance?

Insulin resistance is a condition in which the natural hormone insulin becomes less effective in reducing blood sugar concentrations. As a result, blood glucose levels become elevated. This may cause adverse health effects

Fat and muscle cells require insulin to absorb glucose. The liver regulates glucose levels by reducing glucose secretion when insulin is present in the body. Those with insulin resistance have livers that may not reduce the level of glucose production in this situation.

Diseases of insulin resistance

Type 2 diabetes is arguably the most well-known disease associated with insulin resistance, there are others, including metabolic syndrome, hypertension and non-alcoholic fatty liver disease.

Aside from type 2 diabetes, the most common among those diseases is metabolic syndrome, which acts as group of factors that together increase the risk for coronary heart disease, stroke and diabetes. Those risk factors include high blood pressure, a large waistline, high triglyceride levels, low HDL cholesterol – also known as “good cholesterol” – and a high fasting blood sugar level.

Non-alcoholic fatty liver disease, as its name suggests, is the accumulation of fat in the liver in those who drink little to no alcohol. While it results in no complications in most people, it can sometimes lead to inflammation and scarring of the liver. The most severe cases can eventually lead to liver failure.

Symptoms of insulin resistance

People with insulin resistance may demonstrate some of the following symptoms: fatigue; brain fogginess and inability to focus; high blood sugar; intestinal bloating because most intestinal gas is produced from carbohydrates in the diet that humans are unable to digest and absorb; sleepiness, particularly after meals; weight gain, fat storage or difficulty losing weight; increased blood triglyceride levels; increased blood pressure; increased pro-inflammatory cytokines associated with cardiovascular disease; depression; acanthosis nigricans; or increased hunger.

Risk factors

There are several genetic risk factors for insulin resistance, including a family history of type 2 diabetes, insulin receptor mutations (also known as Donohue’s syndrome), LMNA mutations (also known as familial partial lipodystrophy) and being black, Hispanic, American Indian or Asian. Other risk factors include being aged 40 to 45 years, being obese, sedentary lifestyle, hypertension, high triglyceride levels, low levels of good cholesterol, prediabetes, the development of gestational diabetes, giving birth to a baby weighing more than 9 lb; and having a body that stores fat predominantly in the abdomen rather than in the hips and thighs.

Diagnosis, treatment

Insulin resistance is diagnosed by measuring fasting insulin levels or using glucose tolerance testing. A hyperinsulinemic euglycemic clamp is the gold standard for measuring insulin resistance. A modified insulin suppression test may also be used, as may a homeostatic model assessment (HOMA) or a quantitative insulin sensitivity check index (QUICKI).

Exercise and weight loss are the two primary treatments for insulin resistance. Drug therapies include metformin and thiazolidinediones, but they are only approved for type 2 diabetes.

Additional information may be found at these websites:

http://bloodjournal.hematologylibrary.org/cgi/collection/gene_expression

http://www.nlm.nih.gov/medlineplus/ency/article/003706.htm

http://www.mayoclinic.com/health/metabolism/WT00006/

http://www.nature.com/jcbfm/index.html

http://www.nutritionandmetabolism.com/

http://www.hormone.org/Public/endocrinologist.cfm

http://www.nlm.nih.gov/medlineplus/ency/article/002257.htm

http://www.ncbi.nlm.nih.gov/books/NBK22/?depth=10

http://endo.endojournals.org/

http://www.mayoclinic.org/medicalprofs/glucocorticoid-induced-diabetes.html

http://www.nlm.nih.gov/medlineplus/steroids.html