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Doctor's Diagnosis: Insulin

Registered nurse Susan Eager, right, teaches a diabetic

Registered nurse Susan Eager, right, teaches a diabetic patient how to draw her own insulin injections during a house call in Denver, Colo. (March 26, 2012) Photo Credit: Getty Images

When I first met my brother-in-law, Leo, he was experiencing a personal crisis: He had just been told that he had diabetes and would have to inject himself with insulin for the rest of his life. Initially in a state of shock, he eventually became quite comfortable with the procedure and now doesn’t think twice about injecting himself in front of family and friends. But what exactly is he injecting and why?

Our bodies try to maintain a constant blood-level of glucose, a type of sugar. The glucose cannot leave the blood and enter most cells of the body unless insulin is present. Insulin is a hormone secreted by the pancreas. If there is an insufficient amount of insulin, such as occurs in patients with diabetes, the blood glucose level climbs even though the cells are being starved of glucose. Some of the glucose will spill out into the urine. The body is then forced to use alternate fuels for energy, which can lead to life-threatening complications.

Until the 1980s, insulin was obtained from the pancreases of cows and pigs. Presently, most insulin is obtained from microbes such as yeasts whose DNA is altered to produce human insulin.

Insulin is usually injected because it is a protein, and stomach acid would break it down if swallowed in pill form. The pancreas continuously senses the level of glucose in the blood to determine the body’s insulin needs, automatically increasing its output after meals, for example. Patients on insulin need to check their glucose levels frequently and inject themselves with various combinations of long- and short-acting insulins to try and mimic the pancreas. However this requires multiple needle “sticks” and many patients find it difficult do this, day after day.

Insulin can also be delivered continuously via a catheter placed under the skin which is attached to a small pump that the patient carries at all times. The pump delivers a continuous baseline infusion and can be programed to deliver extra boluses at mealtimes. Many patients find this more convenient but there is still the need for them to frequently check their glucose levels.

Newsday recently reported progress on a “bionic pancreas” that can both continuously monitor the glucose level and supply the correct amount of insulin, much like a normal pancreas. For my brother-in-law and millions of others such a device can’t become available too soon.

Dr. Stephen Picca of Massapequa is Board Certified in both Internal Medicine and Anesthesiology. He is retired from practice. Questions and comments can be sent to Dr. Picca at


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