Circadian variation in onset of myocardial infarction : Comparison between diabetics (Niddm) and non-diabetics.

ABSTRACT

Aims and Objectives: A number of retrospective and prospective studies have demonstrated a peak in the onset of MI in the morning hours and a trough at night. This has led to investigations of the factors which can affect or modify the circadian pattern of onset of MI. The current study was undertaken with an objective of assessing whether the presence of diabetes can or cannot affect the circadian pattern of onset of myocardial infarction in an Indian population. Material & methods: 50 non diabetic subjects and 50 diabetic subjects were randomly selected from among patients admitted to cardiac ICCU of LTMMC and GH Sion, Mumbai. For all patients the time of onset of MI was noted and the results were tabulated. Results: 44% of non-diabetic subjects experienced onset of myocardial infarction in the period between midnight to 600 a.m. as compared to 32% in case of diabetics but an application of Chi Square Test, did not come out to be significant. But on comparing diabetics with >5 years and <5 years history, a significant loss of circadian rhythm was observed in case of diabetics of >5 years duration, indicating that autonomic neuropathy may play a role in the loss of circadian rhythm. Conclusion: It has important implications for the treatment of myocardial infarction in case of diabetics. This study can be followed up with additional studies to verify other factors which can affect circadian pattern of onset of myocardial infarction. Loss of biorhythms can result in increased incidence of thrombotic events throughout the day leading to increased cardiovascular mortality and morbidity.