Progression of Retinopathy After Change of Treatment From Oral Antihyperglycemic Agents to Insulin in Patients With NIDDM

Abstract

OBJECTIVE In insulin-dependent diabetes mellitus, institution of good glycemic control has been shown to retard development of retinopathy even though temporary progression has occurred. Few data have been available from patients with non-insulin-dependent diabetes mellitus (NIDDM). To determine the impact of improved glycemic control on retinopathy in patients with NIDDM, we examined, in a case-control study, the progression of retinopathy in 94 patients who changed treatment from oral antihyperglycemic agents to insulin. RESEARCH DESIGN AND METHODS We used the Wisconsin retinopathy scale and related progression of retinopathy during a 2-year observation period to changes in HbA_1c after institution of insulin therapy. RESULTS Progression of retinopathy ≥3 levels occurred in 23% of the patients and was significantly more common in the patient group in which HbA_1c was lowered ≥3% compared with progression in the group in which HbA_1c was lowered P = 0.0001; relative risk 3.2; 95% confidence interval 1.5–6.9). CONCLUSIONS Improved glycemic control as achieved by insulin therapy may be associated with worsening of retinopathy in patients with NIDDM.