Aims/hypothesis: We examined whether diabetic background retinopathy is associated with reduced coronary vasoreactivity in people with Type 1 diabetes.
Methods: A total of 21 men with Type 1 diabetes were investigated, including 9 men with background retinopathy and 12 men without retinopathy. In addition, 12 non-diabetic, age-matched subjects were studied. All subjects were non-smokers, otherwise healthy and had no other diabetic complications. Resting myocardial blood flow and hyperaemic dipyridamole-stimulated flow (dipyridamole, 0.56 mg/kg during a 4-min period), a measure of coronary vasoreactivity, were measured during euglycaemic hyperinsulinaemic clamp (1 mU x kg(-1) x min(-1)) using positron emission tomography and oxygen-15-labelled water.
Results: Resting myocardial blood flow (0.82 +/- 0.13 vs 0.96 +/- 0.23 vs 0.88 +/- 0.25 ml x g(-1) x min(-1), with vs without retinopathy vs non-diabetic subjects) and coronary vascular resistance (111.2 +/- 23.4 vs 95.5 +/- 15.8 vs 101.9 +/- 31.5 mmHg x min x g x ml(-1) respectively) were not significantly different between the groups. Dipyridamole infusion induced an increase in blood flow and a decrease in coronary vascular resistance in all study subjects (p<0.001). However, dipyridamole-stimulated flow and coronary vascular resistance were blunted in diabetic patients with retinopathy (2.9 +/- 0.9 ml x g(-1) x min(-1) and 34.1 +/- 11.3 mmHg x min x g x ml(-1)) when compared to diabetic patients without retinopathy (4.0 +/- 1.3 ml x g(-1) x min(-1), p=0.04 and 24.6 +/- 7.5 mmHg x min x g x ml(-1), p=0.03) or non-diabetic subjects (4.5 +/- 1.4 ml x g(-1) x min(-1) p=0.008 and 22.2 +/- 8.7 mmHg x min x g x ml(-1), p=0.01). Myocardial flow reserve was impaired in diabetic patients with retinopathy (3.6 +/- 1.0) when compared to non-diabetic subjects (5.3 +/- 1.9, p=0.02) but not significantly reduced when compared to diabetic patients without retinopathy (4.2 +/- 1.4, p=0.2).
Conclusions/interpretation: Diabetic background retinopathy appears to be associated with impaired coronary vasoreactivity in young people with Type 1 diabetes.