Diabetic background retinopathy is associated with impaired coronary vasoreactivity in people with Type 1 diabetes

We examined whether diabetic background retinopathy is associated with reduced coronary vasoreactivity in people with Type 1 diabetes.

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·kg⁻¹·min⁻¹) using positron emission tomography and oxygen-15-labelled water.

Resting myocardial blood flow (0.82±0.13 vs 0.96±0.23 vs 0.88±0.25 ml·g⁻¹·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·min·g·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·g⁻¹·min⁻¹ and 34.1±11.3 mmHg·min·g·ml⁻¹) when compared to diabetic patients without retinopathy (4.0±1.3 ml·g⁻¹·min⁻¹, p=0.04 and 24.6±7.5 mmHg·min·g·ml⁻¹, p=0.03) or non-diabetic subjects (4.5±1.4 ml·g⁻¹·min⁻¹, p=0.008 and 22.2±8.7 mmHg·min·g·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).

Diabetic background retinopathy appears to be associated with impaired coronary vasoreactivity in young people with Type 1 diabetes.