Insulin is a hormone produced by the pancreas that unlocks the body's cells and lets glucose in. Without insulin, your body would be unable to process the glucose it gets from the carbohydrates in the foods you eat. Some people are born without the ability to produce insulin - a condition called Type I diabetes - and must inject themselves with synthetic insulin several times a day. Other people, the overwhelming majority of diabetics, have a condition known as insulin resistance. This condition is called Type II or adult-onset diabetes.
The hormone insulin is an essential part of your endocrine system. It is produced by Beta cells in your pancreas, a vital organ near your liver. Insulin is released whenever your body detects a rise in blood glucose. This rise can be from eating a meal or your body's natural preparation for physical activity or waking up. In people without diabetes, the amount of insulin the pancreas supplies is in direct proportion to the amount of blood glucose in the bloodstream. Insulin prompts cells to take in glucose and blood sugar levels drop to less than 140 milligrams per deciliter (mg/dl) shortly after a meal.
In people with diabetes, however, insulin cannot keep up with the ever-increasing amount of glucose in the blood. This occurs because the cells of a diabetic's body become resistant to the effects of insulin. They no longer open up and let the glucose in when stimulated by insulin. The cells remain unnourished and demand more glucose. You eat more, providing more glucose for absorption. Your pancreas produces insulin at a rapid pace but the cells remain insensitive to the available insulin.
At this stage diet and exercise can have a profoundly positive effect on insulin resistance. Performing some kind of physical activity an hour after a meal can use up much of the blood glucose still in the bloodstream so it won't remain in your body, wreaking havoc on your circulatory system and organs. As little as 10 minutes of walking, household chores like vacuuming or gardening, or a bicycle ride can greatly reduce blood glucose levels after eating.
If your cells become resistant to insulin and you do nothing to alter your diet or lifestyle, after a while your pancreas may give up. Little, if any, insulin is produced and the blood glucose rises even higher. Now you must take additional insulin as diabetes medication and possibly injections. Many doctors also prescribe drugs that decrease the amount of glucose produced by your liver and the amount of glucose absorbed into your body by your intestines. These drugs, like Metformin, lessen your cells' resistance to insulin.
Although diabetes is generally considered a genetic disorder, some people with the gene never develop Type II diabetes. Maintaining a healthy weight, eating a diet low in fat and rich in vegetables, plant proteins (like beans and lentils), consuming no or very lean meats, and keeping physically active can reduce or eliminate the risk of developing insulin resistance.
According to the American Diabetes Association, managing weight gain in pregnancy is also important. Babies born to obese mothers have a significantly higher risk of developing insulin resistance later in life. Insulin resistance is often associated with obesity, steroid use, pregnancy, decreased liver function, and stress.
Insulin resistance is usually a gradual process that can begin decades before diabetes is diagnosed. As long as the pancreas can keep up with the amount of insulin necessary to keep blood glucose at normal levels, you may not even know there is a problem. Your first clue will probably be a rise in post-meal blood sugar, but insulin resistance is usually not discovered until your fasting blood sugar levels have topped 100 mg/dl. Regular medical check-ups are essential. If your family has a history of Type II diabetes, monitoring your fasting and post-meal blood glucose levels can give you valuable information about your potential for developing insulin resistance.