Is it harmful to estimate extra insulin before a meal?

Conditions Expert Dr. Otis Brawley Chief Medical Officer,
American Cancer Society

Expert answer

Dear M. McGee: I strongly suggest that you get instruction on managing your diabetes. Management of diabetes is important, and missteps can be deadly. Many hospitals and doctor groups offer classes on the principles of diabetes management.

Subjects reviewed include diet and exercise, as well as what diabetes oral medicines and injectable insulin do and how they should be taken. Too much insulin of any kind, meaning insulin that is injected and not challenged by an appropriate amount of dietary carbohydrate, can lead to a risk of low blood glucose, which can quickly be devastating.

Diabetes is a series of diseases in which the sugar or glucose in the blood is elevated. At the root of these diseases is the hormone insulin.

Insulin is normally made in the pancreas and secreted into the blood when we ingest carbohydrates (sugars and starches). When we eat carbohydrates, they are broken down into glucose, which is released into the bloodstream. Insulin's function is to cause glucose in the blood to enter into muscle and organs of the body, where glucose serves as a fuel.

There are two major kinds of diabetes.

Type 1 diabetes (also called juvenile onset diabetes) is a disease in which the pancreas stops secreting insulin.

Type 2 (also called adult onset diabetes) is a disease in which the muscles and organs of the body are resistant to insulin secreted by the pancreas and do not absorb glucose from the blood. Type 2 diabetes is often linked to obesity. Again, the result of both types of diabetes is that the blood glucose level rise

Control of blood glucose is important, as a very high level can lead to dehydration, changes in vision, confusion and eventually loss of consciousness and death in hours.

High blood glucose is called hyperglycemia. Long-term moderately high blood glucose levels lead to cardiovascular disease and stroke, kidney failure, blindness, peripheral vascular disease and amputation. Low blood glucose is referred to as hypoglycemia. A very low blood glucose can lead to loss of consciousness, seizure and death in minutes. Moderately low blood glucose levels over a period of time can lead to dementia and other neurologic impairment.

In brief, all patients with type1 diabetes and patients with more advanced type 2 are treated with insulin. Insulin is commonly given by a needle and syringe and is injected just under the skin. There are a number short-acting insulins and long-acting insulins.

A short-acting insulin leads to a rise in the level of insulin in the blood about four hours after injection. Short-acting insulin is often called regular insulin. Longer-acting insulins lead to a rise about eight to 10 hours after injection.

At breakfast, many diabetics take an injection of mixed short- and long-acting insulin. The short meets sugar challenge from lunch and the long-acting meets the sugar from dinner. Use of these drugs requires a diabetic to plan what he or she is going to eat hours before the meal.

Novolog is the brand name of one the newer types of very short acting insulins known as insulin aspart. It has a true convenience in that it can be injected just before a meal and blood levels of insulin rise quickly to meet the carbohydrate challenge of that particular meal.

Today, in lieu of injecting with a needle or pen, some patients carry an insulin pump loaded with the shorter-acting insulin. The pump continuously provides a small amount of insulin through a needle in the skin. The patient can signal the pump to give a higher dose at meals.