Lisinopril, like other ACE inhibitors, lowers blood pressure and preserves renal function in hypertensive patients with non-insulin-dependent or insulin-dependent diabetes mellitus (NIDDM or IDDM) and early or overt nephropathy, without adversely affecting glycaemic control or lipid profiles. On available evidence, renoprotective effects appear to be greater with lisinopril than with comparator calcium channel blockers, diuretics and beta-blockers, despite similar antihypertensive efficacy. As shown by the EUCLID (EUrodiab Controlled trial of Lisinopril in Insulin-Dependent Diabetes) trial, lisinopril is also renoprotective in normotensive patients with IDDM and microalbuminuria. The effect in normotensive patients with normoalbuminuria was smaller than in those with microalbuminuria, and no conclusions can yet be made about its use in patients with normoalbuminuria. In complications other than nephropathy, lisinopril has shown some benefit. Progression to retinopathy was slowed during 2 years' lisinopril therapy in the EUCLID study. Although not yet fully published, these results provide the most convincing evidence to date for an effect of an ACE inhibitor in retinopathy. The drug may also improve neurological function, but this finding is preliminary. Lastly, post hoc analysis of the GISSI-3 trial indicates that lisinopril reduces 6-week mortality rates in diabetic patients when begun as early treatment after an acute myocardial infarction. The tolerability profile of lisinopril is typical of ACE inhibitors and appears to be similar in diabetic and nondiabetic individuals. Hypoglycaemia has occurred at a similar frequency with lisinopril and placebo, as shown in the EUCLID trial. In addition, the GISSI-3 study indicates that the incidence of persistent hypotension and renal dysfunction is increased with lisinopril in general, but the presence of diabetes does not appear to confer additional risk of these events in diabetic patients with acute myocardial infarction receiving lisinopril. In summary, lisinopril lowers blood pressure and produces a renoprotective effect in patients with IDDM and NIDDM without detriment to glycaemic control or lipid profiles. Like other ACE inhibitors, lisinopril should thus be viewed as a first-line agent for reducing blood pressure and preventing or attenuating nephropathy in hypertensive diabetic patients with IDDM or NIDDM and microalbuminuria or overt renal disease. The EUCLID study, using lisinopril, provides new data supporting an additional place in managing normotensive patients with microalbuminuria and IDDM. These findings, together with some evidence for an effect of lisinopril in delaying progression of retinopathy and in reducing mortality, suggest a broader role for the drug in managing diabetic vascular complications.