Trends and enigmas in diabetic patients with acute MIs

Two trends have collided in the last 10-20 years: 1) there is no question that both the prevalence and incidence of type 2 diabetes mellitus are on the increase; 2) conversely, the morbidity and mortality associated with acute coronary syndromes—especially myocardial infarction (MI)—are definitely declining. The evidence for the latter is aptly documented in surveys such as the one reported by McGovern et al,¹ whereas statistics proving the former are not only found in the scientific literature but in the lay press and related media as well. In fact, almost every time one turns on the radio and television there seems to be a report on the growing problem of obesity-related glucose intolerance. The question naturally arises whether these increasing numbers of individuals with diabetes (who will most likely be afflicted with coronary artery disease (CAD) to the same degree those previously diagnosed with diabetes have been) can skew this favorable MI treatment trend in a less positive direction, since diabetes is a major risk factor for the complications of CAD.

In order to provide enough contemporary data to determine whether diabetic patients have benefited from medical advances in the treatment of acute coronary syndromes, Cubbon and colleagues compared the morbidity and mortality statistics related to acute MI in 1995 and 2003, respectively, in a region of the United Kingdom. In the 3404 patients analyzed in terms of baseline risk and effects of treatment, the authors found that there was a significantly greater 18-month mortality rate in the diabetic patients and that this could not be attributed to differences in baseline characteristics aside from diabetes.

The finding that diabetes carries an adverse prognostic effect for acute MI is certainly not news in itself; the medical literature is replete with examples of this phenomenon as the authors note. But the hope has always been that the benefits of improved medical care would be felt in both the diabetes and nondiabetic subgroups. A similar study by Gandhi et al² compared acute MI mortalities in patients with and without diabetes in 1979 and 1998, respectively. Unadjusted 5-year survival rates demonstrated improvement only in the nondiabetic patients. Apparently the data from the current study by Cubbon et al shows nothing much has changed despite all the technological advances of the last decade. What to do? The authors are encouraged by the significant improvement in short-term mortality in their patients with diabetes, but in the final analyses the enigma of why these patients continue to do poorly in the long run after acute MIs continues to be just that— an enigma.