Significant insulin resistance and hyperinsulinemia has been observed to be associated with coronary heart disease in epidemiological studies, particularly so in Asian Indians. This study attempted to investigate if hyperinsulinemia accompanies acute cardiovascular events in Asian Indians, and that it is not a metabolic response to acute stress alone. To test this hypothesis, a case-control study was carried out in a tertiary referral hospital in northern India. Group I (n = 19), consisting of non-diabetic, non-hypertensive, non-obese patients presenting with first episode of acute coronary event (first episode of angina or myocardial infarction) were compared with non-diabetic, non-hypertensive, non-obese patients of group II (n = 21) presenting with non-cardiovascular emergencies (severe abdominal pain e.g. uncomplicated ureteric colic or non-specific intestinal colic. Blood was analysed for glycosylated haemoglobin, fructosamine and insulin levels within 24 hours of the acute event. Elevated serum fructosamine was observed in 11 (57.8%) subjects in group I and 9 (42.9%) in group II (p = NS). Glycosylated haemoglobin was 6.8 +/- 0.1 percent in group I versus 5.9 +/- 0.04 percent in group II (p < 0.01). Three out of 11 subjects in group I and 1/9 subjects in group II having elevated serum fructosamine level also had increased glycosylated haemoglobin level. Five (26.3%) subjects in group I and 2 (9.5%) in group II with elevated glycosylated haemoglobin level were excluded from the analysis as these patients might have been diabetic. Mean serum insulin values were significantly higher in group I (161.3 +/- 8.15 micro IU/mL and 17.5 +/- 1.9 micro IU/mL in groups I and II, respectively; p < 0.001). Eleven (57.8%) subjects in group I had insulin values above 100 uIU/ml. The present study indicates that significant hyperinsulinemia accompanies acute cardiovascular events and it is not an acute response to pain or stress hyperglycemia. Markedly high insulin levels observed in these patients may have a potential role in the pathophysiology of acute coronary event, and may be further studied as a possible prognostic marker.