Self-induced hypoglycemia?

I have some hesitancy writing this blog because so many patients with diabetes are scared to take insulin. They feel that this is the end of the road for their diabetes and have also heard that insulin makes you gain weight. Most of these fears are unfounded but are deeply rooted. Insulin is a life-saving therapy for patients with type 1 diabetes and important as either adjunct or sole therapy in many patients with type 2 diabetes. But it must be used carefully and only after appropriate teaching about its use. As with so many medications we prescribe daily, insulin therapy is subject to abuse.

A 47-year-old woman with long-standing diabetes, by her account type 1, started to have frequent episodes of hypoglycemia at different times of the day. She was treated only with insulin for 30 years — most recently Levemir (Novo Nordisk). One of these episodes resulted in hospitalization, and her hypoglycemia persisted for several days despite the absence of insulin therapy and continuous IV glucose. Either she was making insulin endogenously or was somehow getting access to insulin surreptitiously. She was feeling comfortable and only mildly distressed as I took the history and examined her. She complained of some abdominal discomfort and had tenderness in the left upper and lower abdominal quadrants but there was no guarding or rebound, and abdominal sounds were normal. When we were discussing the possible causes, including the possibility of her surreptitious use of insulin, she was disturbed but not angry, nor did she protest loudly that I might suggest such a thing. With a blood glucose (measured in the lab) of 26 mg/dL her insulin level was 218 and the C-peptide was undetectable. CT of the abdomen and pelvis was normal. Over a four-day period her blood glucose remained below 50 mg/dL and her insulin level gradually decreased to a nadir of 14 and C-peptide remained undetectable. With her permission her room was searched for insulin, but none was found. On day five she was transferred to another hospital room and denied visitors, again with her permission. Her capillary blood glucose rose quickly to >500 mg/dL. The dextrose infusion was discontinued, and for the next 48 hours it was difficult to maintain her CBG below 200 mg/dL. She was treated with insulin 70/30 twice a day with pre-meal aspart insulin. CBG control was restored.

What is her diagnosis, and how should she be managed? The obvious etiology is self-induced hypoglycemia secondary to insulin abuse, but this is extremely difficult to confirm and is a tough diagnosis with which to label the patient unless there is absolute certainty — the patient confesses, or the hidden insulin supply is located. Could this be insulin-secreting tumor, such as an insulinoma or retroperitoneal fibroma? The abdominal CT was negative and the pattern of the insulin levels over time argues strongly against these diagnoses. Could this be caused somehow by prolonged action of Levemir? I can find nothing in the literature to suggest this ever happens but it is something to keep in mind. Certainly she will not be restarted on any long-acting insulin (Levemir or glargine) any time soon and we must patiently wait to see if prolonged hypoglycemia recurs.

A PubMed search yesterday for “diabetes AND depression” returned 226 citations in English that had been published in the last 12 months. It is a very common problem for which we need to be ever mindful. Is this the correct diagnosis in my patient?

Endocr Pract. 2008;14:1006-1010. PMID: 19095600.