Objective: Acromegaly is a rare pituitary disease due to excessive secretion of GH. Insulin resistance, impaired glucose tolerance (IGT) and diabetes mellitus (DM) are common features in acromegaly. Seventy-four active acromegalic patients were retrospectively evaluated in order to determine the impact of family history for diabetes mellitus on glucose tolerance, insulin resistance and beta-cell function.
Patients and methods: We studied 74 patients with active acromegaly (mean IGF-1 value: 576.8±35.6 ng/ml ES; mean GH value on OGTT nadir 11.8±1.8 ng/ml ES), 29 males and 45 females, aged 50.4±14.1 years, body mass index (BMI) 28.1±4.3 (kg/m2). All patients underwent an oral glucose tolerance test (OGTT): GH, blood glucose and insulin were sampled at 0, 30, 60, 90, 120 minutes. Insulin resistance was evaluated with HOMA2-IR, Quicki and ISI0.120; beta cell function was evaluated with HOMA2%-ß index.
Results: Acromegalic patients with a positive family history for diabetes mellitus showed an higher BMI (P<0.05), an higher fasting insulin (P<0.05); insulin evaluated at 90′ (P<0.005) and 120′ (P<0.005); and an higher blood glucose levels evaluated at 120′ (P<0.05) respect to patients with negative family history. No difference was found about GH and fasting blood glucose levels. Moreover patients with positive family history were more insulin resistant showing an higher HOMA2-IR (P<0.05) and Quicki Index (P<0.05), a lower ISI0.120 (P<0.005). No difference was found about HOMA beta-cell function (HOMA-%ß). Acromegalic patients with diabetes mellitus (n.7) had an higher (P<0.05) prevalence of positive family history (71.4%) compared with patients (n.44) with normal glucose tolerance (29.5%).
Conclusions: According to the present study, we found that family history for diabetes mellitus may have a role as an independent risk factor in promoting insulin resistance and diabetes mellitus in acromegalic patients.