Acromegaly: An unusual first presentation with severe diabetic ketoacidosis

A 60-year-old woman presented to our A&E department with a 5 day history of vomiting, frontal headache and feeling generally unwell. She was hyperglycaemic at 31.8 mmol/l, severe metabolic acidosis (pH 7.02; bicarbonate 5.2 mmol/l) (++++) ketonuria and acute kidney injury. Normal lactate (1.8 mmol/l). She had been diagnosed with Type 2 diabetes 18 months before: well managed by metformin alone. Two weeks prior to presentation, however, she had developed increasing thirst and polyuria. On examination she was dehydrated. BP 159/93, temperature 35.3°C, pulse 118/ min. She manifested clinical signs of acromegaly with interdental spacing, prognathism, forehead furrowing, enlarged hands and feet. Urgent CT showed a pituitary adenoma measuring 2.4 cm 9 2.3 cm. Initial management was with intravenous insulin infusion and fluids. It quickly became apparent she had significant insulin resistance needing greater than 10 units/h of insulin to manage the hyperglycaemia. Growth hormone and IGF- 1 levels were significantly elevated. Anti-GAD and islet cell antibodies were negative. On resolution of acidosis she started a basal bolus subcutaneous insulin regime. A glucose tolerance test confirmed non-suppression of growth hormone. She is now established on octreotide and awaits pituitary surgery. Discussion: Acromegaly is rare, but commonly associated with impaired glucose tolerance although up to 56% can develop frank diabetes. It is unusual, however, to present with significant ketoacidosis, although there are rare cases reported. Excessive growth hormone counteracts the effects of insulin and raised IGF-1 levels cause insulin resistance leading to hyperglycaemia. The subtle clinical features of acromegaly are easily overlooked delaying diagnosis leading to significant long-term morbidity and mortality.