New solutions for type 2 diabetes mellitus: the role of pioglitazone

Type 2 diabetes mellitus remains a significant burden to the Canadian healthcare system. Over 2 million Canadians have diabetes, with 85 to 90% having type 2 diabetes. Insulin resistance is a major pathophysiological mechanism in the development of type 2 diabetes. Insulin resistance can be defined as an impaired biological response to the metabolic and/or mitogenic effects of either exogenous or endogenous insulin. As a consequence of insulin resistance, type 2 diabetes is characterised by decreased glucose transport and utilisation at the level of muscle and adipose tissue and increased glucose production by the liver. The traditional oral agents used to treat type 2 diabetes clearly do not address the underlying insulin resistance responsible for the development of diabetes. Thiazolidinediones (TZDs) represent a relatively new class of oral hypoglycaemic medications that have been shown to reverse some of the metabolic processes believed responsible for the development of insulin resistance and, ultimately, type 2 diabetes. Research has demonstrated that TZDs activate peroxisome proliferator activator receptors, in particular, the gamma-receptor isoform. Pioglitazone is a TZD that reduces plasma glucose levels by increasing peripheral glucose utilisation and decreasing hepatic glucose production. Clinical studies with pioglitazone have demonstrated the following: absolute reductions in glycosylated haemoglobin of 0.8 to 2.6%; reductions in fasting plasma glucose of 1.7 to 4.4 mmol/L; an increase in high density lipoprotein cholesterol of 8.7 to 12.6%; and a decrease in triglycerides of 18.2 to 26.0%, with no significant effects on low density lipoprotein or total cholesterol.