Aims: Subjects with Type 1 diabetes have impaired coronary vasoreactivity but the independent role of glycaemic control on myocardial perfusion is less clear. We examined the effect of lifetime glycaemic exposure on coronary vasoreactivity in 43 otherwise healthy Type 1 diabetic subjects.
Methods: Myocardial blood flow was calculated basally and during pharmacologically induced hyperaemia in the fasting state and during euglycaemic hyperinsulinaemic clamp (at an insulin infusion rate of 1 mU/kg per min for 60 min) using positron emission tomography and (15)O-water. Glycaemic exposure was estimated as glycosylated haemoglobin A(1c) (HbA(1c)) months.
Results: Hyperaemic myocardial blood flow was inversely associated with log HbA(1c) months in the fasting state (r = -0.72, P < 0.01) and during clamp (r = -0.35, P < 0.05). These correlations remained significant after adjustment for lipid values, blood pressures, sex, smoking, body mass index (BMI) and age (r = -0.70, P < 0.05 and r = -0.35, P < 0.05, respectively). No significant correlation was detected between hyperaemic flow and HbA(1c) or plasma glucose values measured immediately preceding the PET study.
Conclusions: The present study demonstrates that the lifetime glycaemic exposure appears to be a better predictor of reduced coronary vasoreactivity than recent glycaemic control in Type 1 diabetic subjects. Reduced coronary vasoreactivity in diabetic subjects with poor glycaemic control and/or long duration of diabetes may represent an early precursor of coronary artery disease.