Endocrine Abstracts

Background: In acromegaly, carbohydrate metabolism disorders (CMD) are frequently observed. We aimed to assess the differences in insulin secretion and sensitivity depending on stage of the disease and type of treatment.

Design: Sixty-four patients with acromegaly (46 women; age 53 (interquartile range, IQR 47–59) years), of whom 29 were newly-diagnosed (NA group), 20 treated with somatostatin analogues (SSA group) and 15 after transsphenoïdal surgery (TSS group) participated. All underwent a glucose tolerance test, with measurement of plasma insulin and blood glucose in the fasting state and every 30 min for 2 h after oral administration of 75 g glucose. CMD (impaired glucose tolerance, IGT, impaired fasting glucose, IFG plus diabetes, DM) were diagnosed according to WHO recommendations. We used the Matsuda index and HOMA-IR to estimate insulin sensitivity.

Results: Mean age (48–55 years) and mean BMI (29.2–30.2 kg/m²) were comparable between the three groups. Z-score IGF1 was similar between the SSA and TSS groups (3.2 (2.4–5.2) vs and 3.5 (0.6–5.7)), but severely elevated in NA patients (P=0.0001). In the SSA group, prevalence of CMD was 90%, whereas it was 62% in the NA group and 27% in TSS group. NA patients were mainly insulin-resistant, with high fasting plasma insulin (FPI) of 93 (IQR 56–196) pmol/l, high HOMA-IR (5.6 (1.9–9.1)) and low Matsuda index. TSS patients had normal FPI (56 (IQR 17–92) pmol/l), and normal HOMA-IR and Matsuda index for their BMI, while SSA patients were mainly insulin-deficient, with FPI 38.0 (14–62) pmol/l, HOMA-IR 1.4 (0.7–3.0) and Matsuda index 7.1 (2.7–9.8).

Conclusion: Hyperinsulinaemia compensates the high level of insulin resistance in NA patients. In SSA patients, suppression of insulin secretion leads to increasing of percentage of DM patients in this group. After TSS, insulin resistance decreases and insulin secretion is restored, that leads to the normalization of carbohydrate metabolism.