Myocardial infarction and incidence of type 2 diabetes mellitus. Is admission blood glucose an independent predictor for future type 2 diabetes mellitus?

Background: Although blood glucose levels in patients with acute myocardial infarction (AMI) are frequently elevated, studies investigating the future risk of type 2 diabetes mellitus (T2DM) in patients with AMI are scarce. We sought to investigate whether increased blood glucose levels on admission in nondiabetic patients with first AMI are predictive for future T2DM.

Methods: We used the KORA MI register database in Augsburg, Germany, and included 1,239 nondiabetic patients aged 25 to 74 years who were admitted to hospital between 1998 and 2003 with a diagnosis of a first AMI and who had survived at least 28 days. Incident cases of T2DM and the date of diagnosis were validated by hospital records or by contacting the patient's treating physician.

Results: A total of 108 cases of incident T2DM were registered during a mean follow-up of 4.7 years. Cox proportional hazards regression analysis was done, and admission blood glucose was divided into quartiles (Q). Compared to AMI patients with blood glucose on admission <111 mg/dL (Q1), patients with levels > or =153 mg/dL (Q4) showed an age and sex-adjusted relative risk of 2.76 (95% CI 1.61-4.75) for incident T2DM. This association was only slightly attenuated after multivariable adjustment (hazard ratio 2.59, 95% CI 1.49-4.49).

Conclusions: Admission blood glucose in nondiabetic AMI patients could offer an initial screening tool during the short-term event to select those patients with high risk for future T2DM requiring a close monitoring of glucose metabolism.