Retinal examination intervals in diabetic patients on diet treatment only

The aim of the present study was to examine whether type 2 diabetic patients with good metabolic control achieved on diet treatment only, developed sight-threatening retinopathy during a four-year follow-up period.

A retrospective four-year follow-up study was carried out including all diabetic patients on diet treatment only, registered at the out-patient clinic at the Department of Medicine and referred for fundus photography to the Department of Ophthalmology in 1989 as well as all patients referred from primary care units for fundus photography during 1988 and 1989. One hundred and seventeen diabetic patients treated with diet only were examined with fundus photography after remittance, and after two and four years.

Age at diabetes diagnosis was 58.8 +/- 13.8 years (mean +/- SD), age at baseline was 61.5 +/- 13.6 years, and diabetes duration was 2.7 +/- 3.1 years. During the four-year follow-up period, 48 of the patients (41%) remained on diet treatment only whereas diabetes treatment was changed in 66 (56%), from diet to oral agents only in 57 (49%), and from diet to insulin alone or in combination with oral agents in 9 (8%) of the patients. One hundred and six patients (91%) did not have any retinopathy at baseline and 11 patients (9%) had minimal background retinopathy. At follow-up, there were no signs of retinopathy in 93 patients (79%), 22 (19%) had minimal background retinopathy, and two had developed moderate background retinopathy. Out of those patients who were still on diet at follow-up, five (10%) had developed minimal background retinopathy. Mean blood glucose and HbA1c levels, registered every year during the observation period, were higher at most time points in patients who received oral agents or insulin treatment compared to those who were treated with diet only during the entire observation period. No differences were observed between patients who received oral agents and those who received insulin alone or in combination with oral agents.

It is suggested, that if the initial retinal examination reveals no or minimal diabetic retinopathy at the time of diagnosis of type 2 diabetes mellitus, the second examination can be postponed at least 4 years in patients with good metabolic control on diet treatment only.