September 13, 2001
Diagnosis and Symptoms
Question from New York, New York, USA:
I have always been skinny, I was diagnosed with polycystic ovaries at age 19 (on the basis of my hormone levels), and, when I was 23, I was diagnosed with diabetes (with all the typically symptoms — excessive thirst, urination, significant weight loss and a blood sugar over 600 mg/dl [33.3 mmol/L], which was originally treated with oral medication. However, this did not lower my blood sugar so, after meeting with an endocrinologist, I went on insulin shortly thereafter.
For the last five years, I have never had to take more than 16 units of insulin per day and my hemoglobin A1cs are around 5-6%. Recent visits to new endocrinologist made me concerned that perhaps I do not have type 1 diabetes and do not need to be on insulin. He did a C-peptide test which was 1.5, but I had already taken my insulin the morning of the test. Does the test detect the injected insulin? I did test positive for the GAD antibody. Do you think it is possible that I could go on an oral medication? Can you please explain the relationships between PCOS and diabetes? I have heard many conflicting explanations.
Answer:
C-peptide does not directly measure insulin. C-peptide is a peptide which is cleaved when insulin is secreted from the beta cells. Injected insulin may decrease C-peptide levels, however. It is best to measure C-peptide in response to a glucose challenge or when the blood sugar is greater than 200 mg/dl [11.1mmol/L]. The level of 1.5 is not high. However, it is unclear whether the result can be relied on.
The positive anti-GAD antibody is a significant finding and consistent with type 1 diabetes. Your case sounds like you have type 1 diabetes. However, individuals with type 1 diabetes may have some resumption of insulin secretion after blood sugars are brought down into the near-normal range. I would not try to get to oral agents and sacrifice good control.
Polycystic Ovary Syndrome is a clinical syndrome and is not a specific diagnosis. However, it is associated with insulin resistance and type 2 diabetes.
JTL
