Similar rate of improvement, deterioration of glucose tolerance with somatostatin analogs to treat acromegaly

Twelve months of first-line treatment with somatostatin analogs was associated with a similar rate of deterioration and improvement of glucose tolerance among patients with newly diagnosed acromegaly.

Researchers assessed the impact of first-line therapy on glucose tolerance in 112 patients with acromegaly — 63 had normal glucose tolerance at baseline, 24 had impaired glucose tolerance and 25 had diabetes.

After 12 months, 57 patients had normal glucose tolerance (50.1% vs. baseline), 30 had impaired fasting glucose or IGT (26.8% vs. baseline) and 25 had diabetes (22.3% vs. baseline).

Twenty-eight patients (25%) modified their glucose tolerance — 11 (9.8%) improved and 17 (15.2%) worsened. Ninety percent of patients with glucose tolerance improvement achieved control of acromegaly; however, 89% of patients with glucose tolerance worsening did not control their acromegaly (P<.0001). Thus, worsening of glucose tolerance was associated with poor or uncontrolled disease.

Major predictors for changes in glucose tolerance weredisease control (P<.0001), baseline glucose tolerance(P=.0054) and glucose tolerance levels (P=.008).

Patients with diabetes or IGT at baseline experienced worsening of glucose control more often at the beginning of somatostatin analog treatment.

Age and insulin-like growth factor 1 levels predicted fasting glucose levels whereas disease duration, growth hormone levels and IGF-1 levels predicted HbA1c levels.

“Adaptation of diabetes treatment is required during somatostatin analog treatment so that a careful follow-up is mandatory,” the researchers concluded. “Whether treatment of insulin resistance syndrome might prevent development of overt diabetes in patients with acromegaly undergoing somatostatin analog treatment should still be ruled out.”

Colao A. J Clin Endocrinol Metab. 2009;94:2907-2914.