Absence of circadian variation in the onset of acute myocardial infarction in diabetic subjects

Abstract

Objectives: To investigate the circadian pattern of acute myocardial infarction in non-insulin-dependent diabetic patients and to compare it with that of controls. Background: Previous studies have shown that there is a circadian variation in the incidence of acute myocardial infarction, but there are few data on diabetic subjects. Methods: A hospital based prospective case-control study. Results: 196 diabetic patients and 196 age and sex matched controls were admitted with a diagnosis of acute myocardial infarction during the study period. In 32 diabetic patients and 38 controls, the time of onset of myocardial infarction was unknown; in 34, 44, 42, and 44 diabetic patients the onset was in the first to fourth quarters respectively (χ2 = 1.66, NS). The corresponding figures for the controls were 30, 56, 45, and 27 (χ2 = 13.9, P < 0.005). The difference between the two groups was highly significant (χ2 = 10.3, P < 0.025). Conclusions: Diabetic subjects do not show a significant circadian variation in the onset of acute myocardial infarction.