Sonal Singh, MD, Department of Medicine, Wake Forest University School of Medicine, Winston-Salem, NC, USA.
Yoon K. Loke, MBBS, MD, University of East Anglia, School of Medicine, Health Policy and Practice, Norwich, UK.

Cardiovascular disease is the leading cause of mortality among older adults with type II diabetes. The thiazolidinediones (rosiglitazone and pioglitazone) lower blood sugar levels among individuals with type II diabetes. The thiazolidinediones have favourable effects on surrogate markers of cardiovascular disease such as microalbuminuria, carotid intimal thickness, and blood pressure. Emerging evidence from recent randomized clinical trials has confirmed both that thiazolidinediones increase the risk of heart failure, and that rosiglitazone increases the risk of myocardial infarction among those with type II diabetes. Clinicians should avoid thiazolidinediones for older individuals with type II diabetes who are at risk for cardiovascular events as the negative cardiovascular effects of the thiazolidinediones outweigh any potential benefits on surrogate markers.
Key words: thiazolidinediones, pioglitazone, rosiglitazone, heart failure, myocardial infarctions.

Sheldon Singh, BSc
Toronto, ON and

George Fantus, MD, FRCPC,
Diabetology
Mount Sinai Hospital
Toronto, ON and
Director, Banting & Best Diabetes Centre Core Lab

In the USA, the prevalence of type 2 Diabetus Mellitus (T2DM), in individuals over 65 is estimated to be 10%. This is twice the prevalence of the overall USA population. The worldwide prevalence of T2DM is steadily increasing due to factors such as an increase in the elderly population, obesity, and decreased physical activity.

Multiple mechanisms are involved in the pathogenesis of T2DM including impaired insulin secretion by pancreatic b-cells, increased hepatic gluconeogenesis, and reduced glucose uptake by muscles and adipose tissue (see figure 1). These factors lead to hyperglycemia and in the long term, micro- and macrovascular complications. Available evidence indicates that improved glycemic control will decrease the complications of diabetes; this may be achieved with a combination of dietary, exercise and pharmacologic interventions.

Current pharmacologic agents used to treat T2DM include sulphonylureas (glibenclamide, gliclazide), biguanides (metformin), alpha-glucosidase inhibitors (acarbose), or insulin.