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How R.Ph.s can help patients control insulin resistance

Insulin resistance is a problem that affects tens of millions of Americans. According to David Kendall, M.D., chief of clinical services and medical director, International Diabetes Center, Minneapolis, "it has become apparent that insulin resistance and its consequences are broad-based and far-reaching."

Stuart Haines, Pharm.D., CDE, associate professor, University of Maryland School of Pharmacy, Baltimore, said, "Insulin resistance is a complex metabolic problem, involving not only abnormalities in glucose metabolism that can lead to diabetes in many patients, but also abnormalities in lipid metabolism, cholesterol metabolism, and epithelial function. These often result in hypertension and obesity."

Diet and physical activity can limit the clinical consequences of insulin resistance, Kendall asserted. "Meal planning and exercise are the cornerstones of treatment," added Pat McGowen, R.Ph., CDE, pharmacy manager, Fair Oaks Pharmacy, Arroyo Grande, Calif. "Most of the time, this involves portion control and modifying the meal plan to include more protein.

"In terms of insulin resistance, one of the most important things for a patient to do is reduce caloric intake," McGowen explained further. He added that pharmacists can help patients understand that they have a carbohydrate intolerance and need to decrease their intake of carbohydrates and increase their intake of protein and low-glycemic-index foods such as vegetables.

Some patients make progress with diet and exercise in terms of losing weight but do not decrease their insulin resistance, Haines noted. These persons may supplement their diet and exercise program with drug therapy. The therapy that is most widely used, he said, is metformin (Glucophage and Glucophage XR, Bristol-Myers Squibb), a drug that reduces hepatic glucose production and improves insulin sensitivity. It should be noted that metformin is indicated only for Type 2 diabetes.

Other therapies are probably useful but are less well studied, Haines continued. For example, according to both Haines and McGowen, thiazolidinediones (TZDs) are the subject of ongoing studies. TZDs are exciting because they address the underlying pathophysiology of insulin resistance by sensitizing cells to endogenous insulin. Clinical trials that prove TZDs are beneficial and safe in otherwise healthy patients have not yet been completed, however. "These persons are asymptomatic and will probably live with insulin resistance from the time they are in their late 20s or their early 30s," Haines explained. "Should you be giving someone a drug for 30 years to prevent something that will happen in their 50s?"

"TZDs are very expensive, and some risk is involved in using them," continued Haines. "Until we have more evidence to support their use, I think it is wise to avoid long-term therapy with TZDs unless the patient cannot engage in physical activity."

A drug that Haines does feel may be safe for long-term use is the alpha-glucosidase inhibitor acarbose (Precose, Bayer). Acarbose does not enhance insulin secretion, unlike the sulfonylureas, he said. The drug delays glucose absorption and reduces postprandial hyperglycemia. Acarbose does not improve insulin resistance, Haines emphasized.

The goal of any therapy for insulin resistance is a decrease in morbidity and mortality. Studies have shown that this cannot happen with glucose control alone, however. Said McGowen, "To impact morbidity and mortality in those with insulin resistance, we have to control the weight, hypertension, and cholesterolemia. Then we can work on hyperglycemia." McGowen noted that patients can control the course of their disease. "When we work with these patients, we put them in control. They control how this disease goes."

Charlotte LoBuono

 

Charlotte LoBuono. How R.Ph.s can help patients control insulin resistance. Drug Topics 2002;19:26.