Insulin Resistance

Topic Highlights

●    Insulin resistance is a condition where the normal amount of insulin fails to control glucose levels in blood. It's caused by the insensitivity of cells to this hormone.

●    This visual presentation illustrates in detail the regulation of glucose and the role of insulin.

●    The presentation also provides information on the causes of insulin resistance, symptoms of the disease, its diagnosis, complications, treatment, and self-help for disease management.

Transcript

Insulin resistance is a condition where normal amounts of insulin are inadequate to produce a normal insulin response from fat, muscle and liver cells. This serves to elevate plasma levels of free fatty acids, glucose and insulin, and a typical imbalance of blood lipids. Insulin resistance often leads to complications such as type 2 diabetes along with hypertension, cardiovascular disease and obesity.

Insulin is a peptide hormone secreted by the beta cells in the pancreas' islets of Langerhans. When we eat, insulin is released into the blood stream. Insulin induces the liver, muscles and fat cells to remove glucose from the blood for use or storage. Insulin binds with receptors on cells, acting like a key to unlock the cell for the glucose to enter.

Inside the cell, glucose is utilized for energy or stored in the form of glycogen in liver or muscle cells. The body can store glycogen only in small quantities, which may not last one active day. Once the glycogen stores are full, any extra glucose is stored as saturated fat. Insulin regulates the release of fat. It prevents the liver from releasing any fat after a meal, as glucose is readily available. Insulin also assists the storage of nutrients. Insulin also plays a major role in sodium retention.

Insulin resistance occurs when the normal amount of insulin secreted by the pancreas is unable to unlock the door to cells for glucose. Here the cells become less sensitive to insulin. The glucose level in the blood increases, triggering the pancreas to produce more insulin. Exposure to high levels of insulin triggers the cells to reduce receptor activity and also the number of receptors. The pancreas is sometimes unable to keep pace with the resistance to insulin and even the high level of insulin produced is unable to meet the requirement. Blood sugar increases resulting in type 2 diabetes.

Those who experience insulin resistance commonly experience signs of fatigue after meals containing carbohydrates and some even experience this throughout the day. Other reported symptoms include poor memory, mood swings and agitation, bloating of the intestine and (in children) poor grades in school.

Being overweight or obese, particularly abdominal or central obesity, is commonly associated with insulin resistance. Indeed central obesity, in particular, is thought to be a major predisposing factor.

Genetic factors are likely to play a role in the development of insulin resistance, although the major issues appear to concern lifestyle such as obesity and low physical activity.

A rise in blood glucose may be one of the first indications that the person has insulin resistance. Glucose in the blood is either measured in mg/dl or mmol/l. The levels of glucose indicating diabetes are >7 mmol/l or 100mg/dl fasting and for a random sample >11 mmol/l or 140mg/dl, provided symptoms of diabetes are also present.

If no symptoms are present, a second confirmatory blood test needs to be done. Where there is doubt, particularly where levels of blood glucose are a little raised but not in the diabetes range, then an oral glucose tolerance test becomes the definitive test to define both impaired glucose tolerance and type 2 diabetes. The test measures the level of glucose in the blood after fasting and then two hours after a glucose drink. Avoid food, alcohol, tobacco and heavy exercise twelve hours before the blood test.

Insulin resistance is a major feature in the development of type 2 diabetes. In addition, insulin resistance is also associated with lipid abnormalities in the blood, particularly raised levels of triglycerides, low HDL cholesterol (HDL is good cholesterol) and increased proportions of highly atherogenic small dense LDL cholesterol. This type of profile increases the risk of cardiovascular disease, particularly heart attacks.

High blood pressure is also associated with insulin resistance and this may lead to increased risks of cardiovascular disease and kidney failure. Insulin resistance is also a feature of the polycystic ovarian syndrome in women. High levels of insulin in blood results in elevated levels of male sex hormones or androgens preventing ovulation. As a result, cysts develop in the ovaries which may lead to menstrual irregularities and an inability to conceive.

People with extreme insulin resistance may develop acanthosis nigricans, patches of darkened skin on the back of the neck, underarms, groin areas or skin folds. This is thought to be due to high levels of insulin in the blood.

Some medicines used to treat type 2 diabetes exert their actions, at least in part, through improvement of insulin resistance. These include metformin, the glitazones and the alpha-glucosidase inhibitors (acarbose). Anti-diabetes medications should improve insulin sensitivity through the process of reducing plasma glucose. There is also evidence that specific treatments for insulin resistance may help to prevent the development of type 2 diabetes.

Lifestyle changes can help to significantly reduce insulin resistance. These include eating a healthy diet, weight loss, where appropriate, and increased levels of physical activity. Diet should include reduced intake of refined carbohydrate such as sweets, sugar, biscuits, white bread and white rice. A diet low in saturated fat is recommended and avoidance of dairy fat, animal fats, palm oil and coconut oil is important. Diet can be balanced with increased amounts of protein, healthy fats and unrefined carbohydrate high in fiber.

The food pyramid will help guide in planning for meals. The main part of food should come from unrefined carbohydrate high in fiber. Examples include brown bread, brown rice, etc. Other examples include protein-rich foods such as meat and nuts, together with lots of vegetables, including green leaves and brightly colored vegetables such as tomato, lettuce, cucumber, cabbage, eggplant and green beans. Fruits such as oranges, apples, pears, grapes, plumbs, peaches and strawberries can be taken, although with caution and without sugar content. Some fruits such as bananas, pineapples and dried fruits may have high sugar content.

Walking is one of the best forms of exercise. The recommendation is to perform 30 minutes brisk walking between 5 and 7 days per week, gradually building up, where possible, both from the point of view of increasing length of exercise and also intensity. Other useful exercises are jogging, swimming and cycling. Select an appropriate activity and stick to it. Be aware that for those who are unfit, increasing physical activity to the required levels may take time.