Diabetes Mellitus is Frequent, But Retinopathy is Rare in Acromegaly: A Cross-sectional Study

Background: The roles of growth hormone (GH) and insulin-like growth factor-1 (IGF-1) in diabetic retinopathy (DR) are well recognized, but the prevalence and pathogenesis of retinopathy in acromegaly are not fully understood. We established the frequency and severity of glucose intolerance and retinopathy—and the relationship between them—in patients with acromegaly.

Methods: All patients with acromegaly under the care of the Department of Endocrinology, Baskent University Hospital were enrolled. Fundoscopy was carried out by two experienced ophthalmologists. Acromegaly disease state was evaluated by basal GH and IGF-1 measurements, and an oral glucose tolerance test (OGTT) when appropriate. Glucose tolerance states were assessed by means of fasting and postprandial plasma glucose concentrations, glycohemoglobin measurement and an OGTT when appropriate. The relationships between retinopathy, acromegaly disease activity and glucose tolerance states were examined.

Results: The cohort comprised 49 patients with acromegaly (24 women), with a median disease duration of 25 months (range 1–420 months). Thirty-three had active disease, with median concentrations of GH of 5.54 ng/ml (0.72–172 ng/ml) and IGF-1 of 541.5 ng/ml (203–1,985 ng/ml). The prevalence of diabetes mellitus (DM) was 30.6% (n =15; 10 patients had active acromegaly, five of whom had uncontrolled DM). Two patients had retinopathy (4.1%); both had active acromegaly and uncontrolled DM at the time of examination.

Conclusions: The prevalence of DM was twice that of a reference population, but that of DR was lower than expected. Our findings suggest that disease activity in acromegaly might not contribute to retinopathy.