DOCTOR'S VIEW ARCHIVE

Insulin Therapy for Diabetes Past, Present and Future

Medical Author: Ruchi Mathur, M.D.
Medical Editor: William C. Shiel, Jr., MD, FACP, FACR

I am lucky to have so many wonderful patients who try so very hard to maintain the best blood sugar control possible. For many of them, this involves insulin pump therapy or multiple injections of insulin a day - in addition to testing their blood sugars often. I often get asked is there is anything on the horizon that will make life easier for them. I tell them they may have to "squint" a bit to see it - but off to the distance, there just may be.

The Past

The symptoms of diabetes were described more than 2000 years ago. Aretaeus of Cappadocia (circa 150 A.D) noted that "...it consists of a moist and cold wasting of the flesh and limbs into the urine. The patient never ceases making water. The disease is chronic in character, though the patient does not survive long when it is completely established for the maramus produced is rapid and death is speedy." Ancient Hindu texts also described a diabetic syndrome, characterized by "honeyed urine." These astute observations characterized the clinical syndrome associated with what is now called type 1 diabetes (formerly known as insulin dependent diabetes). Type 1 diabetes usually manifests in childhood or young adulthood. Until the latter half of the 20th century, type 1 diabetes was a fatal disease.

From the time of these ancient observations, there was little in the way of treatment for patients with type 1 diabetes. This primarily was because the cause of the disease was not recognized. In the 1700's, it was found that there were high amounts of sugar in the urine of patients with diabetes. Consequently, the disease was initially thought to be a problem with the kidneys. In the early 1800s, the link between diet and the amount of sugar seen in the urine was established. It was observed that if patients with diabetes ate carbohydrates, their urine contained more sugar than if they ate protein. Over the next century, physicians began reporting autopsy finding that showed abnormal changes in the pancreas of patients who had died of type 1 diabetes. It wasn't until the early 20th century that scientists realized the pancreas produced a substance that regulated blood sugar. In 1921, Banting and Best identified that substance as insulin. They were awarded a Nobel prize for their discovery.

Even with the realization that type 1 diabetes was caused by a deficiency of insulin, patients continued to die. In the first half of this century, insulin was in short supply. At that time, the insulin used was being derived from animal sources, particularly cows and pigs. Not only was there a problem with the supply of insulin meeting the demand, but beef and pork insulin also had specific problems. Being from animals, these types of insulin caused immune reactions in people. Patients would become intolerant or resistant to animal insulin. With the acceleration of scientific research in the latter half of this century, beef and pork insulin were replaced by human insulin. In 1977, the gene for human insulin was cloned, and through modern technology, manufactured human insulin was made available. Up until very recently, insulin has been used only in injection form; drawn up by a needle and syringe and injected just under the skin (subcutaneously).

This century has seen remarkable progress in the treatment of type 1 diabetes. Patients now have the opportunity to live longer, healthier lives than at any other time in history. The last few years have focused on fine-tuning insulin therapy to meet individual requirements and on minimizing the possible long term consequences of diabetes. It is well established that poor blood sugar control contributes to the development of diabetes-related complications such as blindness, kidney failure, nerve damage, and heart disease. Recent advances have focused on manufacturing insulin with specific profiles that can be used individually or in combination to fit a specific patient's needs. In addition, new methods of delivery have been developed to allow for more patient convenience and less discomfort.

The Present

At present, injectable insulin is commonly available. Insulin now comes in a variety of preparations that differ in time of onset and length of action. Because of these differences, combinations of insulin are often used to allow for a more tailored regimen of blood sugar control. The table below lists the most common types of insulin currently in use in the United States, and their specific properties.

Name of Insulin Onset of Action Peak Effect after Injection
Humalog/Novolog/Very Short Acting 5-15 minutes 30-60 minutes
Regular/Short Acting 30 minutes 2-5 hours
NPH/Intermediate Acting 1-2.5 hours 8-14 hours
Lente/Intermediate Acting 1-2.5 hours 8-12 hours
Ultra Lente/Long Acting 4-6 hours 10-18 hours
Combinations - 70/30, 50/50, 75/25 30 minutes 7-12 hours