Retinopathy commonly occurs in people with type 1 diabetes. Strict glycaemic control can decrease development and progression of retinopathy only partially. Blood pressure is also a risk factor for microvascular complications. Antihypertensive therapy, especially with inhibitors of angiotensin-converting enzyme (ACE), can slow progression of nephropathy, but the effects on retinopathy have not been established. We investigated the effect of lisinopril on retinopathy in type 1 diabetes.

As part of a 2-year randomised double-blind placebo-controlled trial, we took retinal photographs at baseline and follow-up (24 months) in patients aged 20–59 in 15 European centres. Patients were not hypertensive, and were normoalbuminuric (85%) or microalbuminuric. Retinopathy was classified from photographs on a five-level scale (none to proliferative).

The proportion of patients with retinopathy at baseline was 65% (117) in the placebo group and 59% (103) in the lisinopril group (p=0·2). Patients on lisinopril had significantly lower HbA_1c at baseline than those on placebo (6·9% vs 7·3 p=0·05). Retinopathy progressed by at least one level in 21 (13·2%) of 159 patients on lisinopril and 39 (23·4%) of 166 patients on placebo (odds ratio 0·50 [95% Cl 0·28–0·89], p=0·02). This 50% reduction was the same when adjusted for centre and glycaemic control (0·55 [0·30–1·03], p=0·06). Lisinopril also decreased progression by two or more grades (0·27 [0·07–1·00], p=0·05), and progression to proliferative retinopathy (0·18 [0·04–0·82], p=0·03). Progression was not associated with albuminuric status at baseline. Treatment reduced retinopathy incidence (0·69 [0·30–1·59], p=0·4).

Lisinopril may decrease retinopathy progression in non-hypertensive patients who have type 1 diabetes with little or no nephropathy. These findings need to be confirmed before changes to clinical practice can be advocated.