Increase in blood glucose concentration during antihypertensive treatment as a predictor of myocardial infarction: population based cohort study

Objective To investigate the impact of an increase in blood glucose on the risk of developing myocardial infarction, with particular emphasis on people taking antihypertensive drugs. Design Prospective population based cohort study. Setting Uppsala, Sweden. Participants 1860 men who had participated in 1970-3 at age 50 in a health survey aimed at identifying risk factors for cardiovascular disease and were re-examined at age 60 and then followed for 17.4 years. Main outcome measure Myocardial infarction after age 60. Results The incidence of myocardial infarction was significantly higher in men treated for hypertension than in those without such treatment (23% v 13.5%, P < 0.0001). Participants who developed,myocardial infarction after the age of 60 (n=253) showed a significantly larger increase in blood glucose between age 50 and 60 than did those without myocardial infarction. In multivariate Cox proportional hazard models increase in blood glucose was an independent risk factor for myocardial infarction (P=0.0001) in men receiving antihypertensive treatment at age 60 (n=291, mainly β blockers and thiazide diuretics) but not in those without such treatment. The impact of increase in blood glucose declined after inclusion of serum proinsulin concentrations at baseline but was still significant. A significant interaction existed between proinsulin concentration (a marker of insulin resistance) at baseline and antihypertensive treatment on increase in blood glucose. Conclusions Increase in blood glucose between the ages of 50 and 60 and baseline proinsulin concentration were important risk factors for myocardial infarction in men receiving antihypertensive treatment, indicating that both an insulin resistant state and the metabolic impact of P blockers and diuretics increase the risk of myocardial infarction.