Background: Acromegaly is frequently associated with impaired glucose tolerance (IGT) or diabetes and treatment has also differential effects on glucose metabolism depending on specific type of medication.
Objective: To study in 57 acromegalic patients evolution of glucose metabolism according to disease activity and treatment.
Methods: IGF1 measurement, oral glucose tolerance test (OGTT) and HOMA test to evaluate insulin sensitivity (HOMA-S) and β-cell function (HOMA-β) were performed in all patients at diagnosis and at last follow-up (median follow-up 7 years).
Results: At diagnosis of acromegaly, 14 patients (25%) were diabetic, 15 (26%) had IGT and 28 (49%) had normal GT. At the last visit, 32% were diabetic and 26% remained glucose intolerant. There was a decrease in fasting glucose (−10.4 mg/dl) in the 20 patients cured by surgery (group I), whereas it increased in the 28 patients controlled under medical therapy (group II, +5.5 mg/dl) and in the nine patients with active disease (group III, +8.8 mg/dl; P=0.016 vs group I). There was no significant difference in evolution of HbA1c and HOMA-S between groups, but loss of β function was more pronounced in groups II (−74.1±12.5%) and III (−38.7±6.4%) vs group I (−26.1±12.9%; mean±S.E.M.; P=0.035). Type of treatment influenced changes in HbA1c between diagnosis and last visit with a decrease (−1.7%) in patients under pegvisomant and an increase in patient treated by somatostatin analogs (+0.3%; P=0.044). In the cured patients, 30% had improved their GT status vs only 11% in the other groups, while deterioration was more frequently observed in patients with medical therapy.
Conclusions: This study shows that more than 50% of acromegalic patients have still IGT or diabetes at distance from diagnosis. Improvement of glucose metabolism is mainly observed in cured patients and in patients treated with pegvisomant.