Insulin treatment of elderly type 2 diabetic patients: effects on retinopathy

Insulin treatment is reportedly associated with the transient progression of retinopathy, possibly with the development of macular oedema in middle-aged Type 2 diabetic patients. The purpose of this study was to investigate the effect of insulin treatment on eye-grounds in elderly (> 65-year-old) Type 2 diabetic patients with secondary failure of oral antidiabetic-drug therapy. Eye examinations were performed in 37 patients randomized to insulin (n = 19) or sulphonylurea (n = 16) treatment and re-investigated after one year. Insulin treatment reduced HbA1c from 9.3% to 7.3% (p < 0.001) after one year. In the sulphonylurea-treated group, HbA1c did not change (9.1 vs. 9.3%). At the start, 65% of the patients had retinopathy, and after one year progression was noted in 7/35 patients (20%; 5 insulin- and 2 sulphonylurea-treated). In the insulin-treated group, the 5 patients with progression had higher initial fasting blood-glucose levels than other patients in the group (15.8 vs 13.1 mmol/L, p < 0.05). Initial HbA1c levels did not differ between the groups (9.8 vs. 9.1%, n.s.), nor the reduction of HbA1c levels during treatment (2.2 vs. 1.3% n.s.). Thus, diabetic retinopathy in this study was common among elderly Type 2 diabetic patients. The progression of retinopathy may in fact be associated with insulin treatment or improvement of metabolic control.