Background: Insulin resistance is a hallmark feature of type 2 diabetes mellitus. It is not uncommon that some patients with type 2 diabetes mellitus require large doses of insulin. However it is important to consider other causes of insulin resistance in patients whose glycemic control remains suboptimal despite increasing doses of insulin. We present a case of a patient with poorly controlled type 2 diabetes mellitus and marked insulin resistance due to hyperandrogenism.
Case Description: A 47 year old female presented with poorly controlled type 2 diabetes mellitus, HbA1c 10.3% (89 mmol/mol), despite large doses of insulin up to 338 units daily. In addition, the patient reported sudden onset amenorrhoea with hirsutism on a past history of possible polycystic ovarian syndrome (PCOS). Biochemical testing showed an extremely high total testosterone level of 14.4 nmol/L (reference range 0.2-1.8 nmol/L) with normal adrenal androgens. This level is a lot higher than what one would expect from PCOS alone. Subsequent localisation studies revealed bilateral bulky ovaries. As the patient was close to menopausal age and fertility was no longer an issue, she proceeded to undergo a bilateral salpingo-oopherectomy and total abdominal hysterectomy. Histopathology revealed bilateral ovarian hyperthecosis, a rare cause of hyperandrogenism. Her testosterone level fell to 0.8 nmol/L day one after surgery. Three months following surgery, her testosterone level remained normal and there was a significant improvement in her glycemic control with HbA1c of 7.7% (61 mmol/mol), and the patient reported multiple hypoglycemic episodes despite reduction in her insulin dosage.
Conclusion: Although insulin resistance is a paramount feature of type 2 diabetes mellitus, other causes of insulin resistance need to be considered in patients with suboptimal glycemic control despite large insulin doses. Hyperandrogenism is a well recognized cause of insulin resistance and should be sought after in patients with suggestive clinical features.