Chronic bromocriptine treatment and glucose intolerance in acromegaly

Blood glucose, plasma GH, insulin and glucagon levels during OGTT before and after treatment with bromocriptine (20 - 40 mg daily 3 - 18 months) were studied in 12 nondiabetic acromegalics (NA) and 6 diabetic acromegalics (DA) not treated previously. There was no significant change in blood glucose levels before and after treatment in NA while blood glucose levels fell significantly in DA after treatment. Mean basal GH levels and after OGTT decreased significantly in NA group, while only in the 120 min of OGTT in DA group. There was no significant change in mean basal or glucose stimulated plasma insulin or glucagon levels before and after treatment in both non-diabetic and diabetic acromegalics. Normal glucagon levels in diabetic acromegalics prior to treatment is considered as relative hyperglucagonaemia which disappeared after treatment. We did not show that glucagon suppressibility after OGTT was reestablished after treatment with bromocriptine in non-diabetic and diabetic acromegalics. Other factors than changes in hormones should be considered as a cause of restored glucose tolerance.