Last week, I had some tests done. My cortisol level was fine and there were no insulin antibodies. My fasting blood glucose was 2.6 mmol/L [48 mg/dl], my C-Peptide was 0.62, and serum insulin was 7. The endocrinologist didn’t have much to say about it and said she’d call another endocrinologist to discuss these results. Are these results okay? If not, is there anything that can be done about it? I’ve taken prednisolone for asthma and that helps increase my blood glucose so I don’t have to eat all the time.

The question really is whether you need a more definitive test, such as a 72 hour fast, to try and diagnose whether you have inappropriate insulin secretion from something like an insulin-producing tumor. The glucose is rather low and the insulin level, although relatively low, can be thought of as being inappropriately high for the glucose. A 72 hour fast involves fasting for up to three days, except for water. Blood sugars are monitored frequently. Once you hit a glucose value less than 40 mg/dl [2.2 mmol/L] to 45 mg/dl [2.5 mmol/L], similar to the glucose of 2.6 mmol/l [48 mg/dl], there is usually a measure of C-Peptide, insulin, and proinsulin. Since your glucose has already been obtained with the fast, you may want your doctor to see if they can also measure proinsulin on the specimen, as the proinsulin to total insulin ratio is inappropriately elevated with insulinoma.

JTL