Combined octreotide and insulin therapy in acromegaly

To describe an unusual treatment strategy for certain patients with both acromegaly and insulin-requiring diabetes.

We present a case history of a man with a pituitary adenoma and diabetes mellitus and chronicle his response to various treatment modalities.

Acromegaly, a disease state with excess growth hormone (GH) and insulin-like growth factor-I, is associated with carbohydrate intolerance. Octreotide, a somatostatin analogue, is used in the treatment of acromegaly to lower GH levels. Despite effective lowering of GH levels, certain patients with acromegaly have persistent or even worsening carbohydrate intolerance and may require insulin therapy. Such a regimen would necessitate five or more injections per day. We describe a 51-year-old man who was diagnosed with a GH-producing pituitary adenoma in 1987. Despite transsphenoidal resection, frontal craniotomy, and radiation therapy, symptoms and increased levels of GH persisted. The patient was diagnosed with diabetes mellitus in August 1989 and treated with glipizide. Because of persistently increased GH levels, he was treated with octreotide. His glycohemoglobin level increased to 21% despite use of maximal doses of glipizide. The patient refused insulin therapy because of his objection to numerous daily injections. Despite adjustments in diet and exercise, glycemic control remained poor. As a trial, we thus attempted combining octreotide and regular insulin in the same syringe and administering the medications in a single subcutaneous injection. No precipitate formation was evident, and he had no adverse effects. Glucose control improved, and the glycohemoglobin level was lower but still elevated. GH levels remained at less than 5 ng/mL. His symptoms of acromegaly were unchanged, but his overall attitude and energy level improved.

The efficacy of the individual components of this treatment was demonstrated in the combination of insulin and octreotide. The combined administration of insulin and octreotide has limited application in patients with acromegaly and insulin-requiring diabetes mellitus.