Objectives: To study the infarct size and mortality in patients with non-insulin-dependent diabetes mellitus (NIDDM) and in non-diabetic subjects with their first acute myocardial infarction.
Design: Seven year follow-up study of large representative cohorts of patients with non-insulin-dependent diabetes mellitus and non-diabetic subjects (study 1) and the FINMONICA acute myocardial infarction register study in 1988-89 (study 2).
Setting: Populations of the districts of the Kuopio University Hospital and Turku University Central Hospital (study 1). Populations of Kuopio and North Karelia provinces and Turku/Loimaa area (study 2).
Subjects: Study 1: 1059 patients with non-insulin dependent diabetes mellitus and 1373 non-diabetic subjects aged 45-64 years at baseline; during the follow-up 166 patients with non-insulin-dependent diabetes mellitus (91 men and 75 women) and 30 non-diabetic subjects (25 men and five women) were hospitalized for their first acute myocardial infarction. Study 2: 1622 patients aged 25-64 years hospitalized for their first acute myocardial infarction; 144 patients (90 men and 54 women) had non-insulin-dependent diabetes mellitus and 1153 (890 men and 263 women) were non-diabetic.
Main outcome measures: The infarct size was assessed on the basis of maximum levels of serum cardiac enzymes (studies 1 and 2) and QRS-score (study 1).
Results: No differences were found in maximum levels of serum cardiac enzymes between diabetic and non-diabetic patients. Similarly QRS-score gave no suggestion of a difference in infarct size between diabetic and non-diabetic patients. In both studies mortality before hospital admission was similar in diabetic and non-diabetic patients, but mortality within 28 days from hospital admission was twice as high in diabetic patients as in non-diabetic patients. Cardiac failure was the main cause of death significantly more often in diabetic patients than in non-diabetic patients (study 2).
Conclusions: Poorer prognosis of acute myocardial infarction in diabetic patients appears not to be explained by a larger infarct size but probably by adverse effects of the diabetic state itself on myocardial function.