Diabetes therapy and cardiac risk

To the Editor: Recently, Drs. Zimmerman and Pantalone ¹ cited the Diabetes Control and Complications Trial (DCCT) ² and the United Kingdom Prospective Diabetes Study (UKPDS) ³ as evidence that glycemic control lowers cardiac risk in type 2 diabetes. And in a related counterpoint article, Drs. Menon and Aggarwal ⁴ also discussed the UKPDS.

These studies should not be cited in this context, since the DCCT is a study of type 1 and not type 2 diabetic patients, and the UKPDS was performed in an era when statins were not available. The UKPDS was launched in 1977 and completed in 1997, and statins were not available until 1987. Indeed, the UKPDS showed that the strongest risk factor for myocardial infarction was an elevated level of low-density lipoprotein cholesterol, followed by a low level of high-density lipoprotein cholesterol. ⁵ It is therefore not surprising that in the initial UKPDS report the incidence of myocardial infarction was not increased in the group with a 0.9% higher hemoglobin A _1c, but that in the 10-year follow-up, when statins were probably used by most patients, myocardial infarction was reduced by a significant 15% ( P = .01). ^3,6 As would be expected in the more modern studies, ie, the Action to Control Cardiovascular Risk (ACCORD), ⁷ the Action in Diabetes and Vascular Disease (ADVANCE), ⁸ and the Veteran Affairs Diabetes Trial (VADT), ⁹ cardiovascular events were not reduced with improved glycemic control.

While the UKPDS clearly demonstrated a decrease in microvascular disease due to improved glycemic control, it should not be used as evidence that improved glycemic control in type 2 diabetes decreases cardiac events. ^3,6