How best to reduce complications of type 2 diabetes?

In patients with type 1 diabetes, sometimes called juvenile-onset diabetes, tight control of blood sugars with insulin has been shown in clinical trials to reduce the risk of blindness, vascular disease and kidney problems that commonly develop with diabetes.

These findings have led scientists to think that tight control of blood sugars would also reduce the risk of these complications in people with the more common form of diabetes: type 2 diabetes, sometimes called adult-onset diabetes, that typically develops when you are older and is associated with being overweight. 

But that hope has not been borne out in a number of recent studies that have found in patients with type 2 diabetes tight control of blood sugars has proven to be of little or no benefit in preventing these complications.

In fact, in some studies, tight control was associated with an increase in heart disease.

In this week’s issue of JAMA, the Journal of the American Medical Association, Seattle researcher Dr. Bruce Psaty of the University of Washington, and colleague Dr. Mark Goodarzi of the University of California, Los Angeles, speculate that when the patient has type 2 diabetes blood-sugar levels may not be the most important target when you’re trying to reduce the risk of these complications.

That’s because type 1 and type 2 diabetes are quite different.

Although patients with type 1 and type 2 diabetes both have high blood sugars, patients with type 1 diabetes produce little or no insulin because their insulin-producing cells have been destroyed.

Patients with type 2 diabetes, on the other hand, initially make insulin but have high blood sugars because their bodies do not respond to the insulin normally, a condition called insulin resistance. 

Indeed, this insulin resistance causes their bodies to produce higher than normal levels of insulin.

In their JAMA article, Psaty and Goodarzi suggest that the high concentrations of insulin seen in patients with type 2 diabetes may be actually harming their blood vessels leading to vascular disease.

“If insulin levels are toxic to the cardiovascular system, then treatments designed to reduce insulin levels rather than glucose levels might be associated with a reduced risk of cardiovascular events in patients with type 2 diabetes,” they write.

They note that a number studies using diabetes drugs that lower insulin levels indicate that such agents can reduce the risk of heart disease and some other complications of diabetes.

The two researchers suggest that future trials should be designed to see whether agents and other strategies that lower insulin levels—not just blood sugars—can prevent or reduce the severity of the cardiovascular and other complications of type 2 diabetes.

To learn more:

• Read the commentary by Drs. Psaty and Goodarzi in JAMA (fee or subscription required).
• Visit the National Diabetes Information Clearinghouse for information and resources about both type 1 and type 2 diabetes.
• Visit the webpage of the American Diabetes Association.

Tags: Blood Sugars, Diabetic Nephropathy, Diabetic Retinopathy, Diabetic Vascular Disease, Insulin, JAMA

Category: Diabetes, Drugs & Medicines