Endocrine Abstracts

Insulin and somatotropin (GH) have opposite effects in glucose metabolism. GH increases the production of glucose through lypolisis and inhibits hepatic and peripheric neoglucogenesis induced by insulin. When insulin secretion is insufficient to overcome insulin resistance, intolerance to glucose or diabetes appears. Drugs used in the treatment of acromegaly also influence glucose metabolism: SSA decrease insulin secretion and pegvisomant has the opposite effect.

The authors present the cases of three male patients, mean age 23.9 years, who were diagnosed with diabetic ketoacidosis (DKA) as first manifestation of acromegaly. No personal or family history of diabetes. All had marked physical features of acromegaly and macroadenomas on MRI.

In two patients, initial HbA1c/GH/IGF1 were 9.3%; 155 ng/ml; 458 ng/ml and 11.8%; 229 ng/ml; 1577 ng/ml. They were initially treated with insulin (maximal doses of 0.26 and 1.28 U/kg per day) and metformin 2 g and 3 g/day. No predisposing factor for DKA was identified. They had surgery with partial resection of the adenoma and began treatment with SSA, with marked improvement in glycemic control and progressive reduction of insulin dose, which was suspended 5 and 7 months later. They maintain increased levels of GH and IGF1 and will be treated with surgery and radiosurgery, respectively.

The third patient presented with pituitary apoplexia and hypopituitarism at the moment of diagnosis (HbA1c 9.3%; IGF1 38.8 ng/ml). After resolution of DKA, he didn’t temporarily need treatment with anti-diabetic medication. However, 2 months later, he had to start treatment with insulin (HbA1c 12%; IGF1 30 ng/ml). He is currently also being treated with levothyroxine and prednisolone and awaits for surgery.

DKA due to relative/absolute insulin deficit is rare as first manifestation of acromegaly (1%). In our series, it represented 6.4% (n=47). The effects of GH and IGF1 on glucose metabolism are complex and could be reversible with the normalization or reduction of GH levels.