Endocrine Abstracts

Objective: To evaluate the presence of glucose metabolism abnormalities and their impact on IGF-1 levels in patients with acromegaly.

Methods: Ninety-three acromegalic patients (52 male/41 female) were included in this study who were seperated into three groups as normal glucose tolerance (NGT), prediabetes and diabetes mellitus (DM). Insulin resistance (IR) was calculated with homeostasis model assessment (HOMA). HOMA-IR >2.5 or ≤2.5 were defined as insulin resistant or noninsulin resistant groups, respectively. We compared the groups in terms of many factors that may be associated with glucose metabolism abnormalities. IGF-1% ULN (upper limit of normal)/GH ratios were used for impact of glucose metabolism abnormalities on IGF-1 levels.

Results: Frequencies of NGT, prediabetes and DM were 25% (n=23), 41% (n=38) and 34% (n=32), respectively. Patients with DM were significantly older and with an increased frequency of hypertension than NGT and prediabetes groups (P<0.001, P=0.01, respectively). IGF-1% ULN/GH ratio was significantly lower in prediabetes group than in NGT group (P=0.04). Similarly IGF-1% ULN/GH ratio was significantly lower in insulin resistant group than in noninsulin resistant group (P=0.04). Baseline and suppressed GH levels were significantly higher in insulin resistant group than in noninsulin resistant group (P=0.024, P<0.001, respectively).

Conclusion: IGF-1% ULN/GH ratio is a useful marker indicating glucose metabolism disorders and IGF-1 levels might be inappropriately lower in acromegalic patients with IR or prediabetes. We suggest that IGF-1 levels should be re-evaluated after the improvement of IR or glycemic regulation for the successful management of patients with acromegaly.