November 30, 2005
Diagnosis and Symptoms, Other
Question from Palm Harbor, Florida, USA:
I was diagnosed with type 2 diabetes seven years ago when I was 31. I actually found out by mistake. I had no symptoms. I’m 5 feet, 4 inches and have ranged in weight from 120 to 130 pounds, am very active, have low cholesterol and low blood pressure. My sister had gestational diabetes and trying out her monitor, I found out my levels were worse than hers. I controlled it with diet for years.
Last year, I was in a car accident and couldn’t continue my daily workout routine. I had problems getting my glucose readings below 200 mg/dl [11.1 mmol/L]. My doctor took some tests and my GAD65 test came back a 49 (extremely high since normal is 0-1). The doctor was pretty shocked at that. My C-Peptide was 0.6 so he suspected latent type 1 and put me on insulin.
I am now back to my regular workout routine. I’m taking 12 ml of Lantus and 0.5 mg of Amaryl. My levels are coming down. My A1c, which was 9.4 last year, is now 7.1 (still high but better). I still struggle with high readings if I even attempt to eat, let’s say, a burger and fries or something.
However I just got my results back from a second round of those tests (don’t see the doctor until January) and they now say I’m not a type 1. I’m a type 2. My GAD65 is now 91 (and that’s not 0.91) It’s out of range at 91. BUT, my C-Peptide was 1.7, very normal and twice what it was last year.
Are there factors that can effect my C-Peptide? It certainly doesn’t seem like my pancreas is keeping up on an every day level. Does it matter if I hadn’t eaten for at least 18 hours before the test? Does it matter that I didn’t take my insulin that morning? Or, that I had taken extra two days before because I had been snacking a couple Halloween treats?
I’m just curious because I just never have had the type 2 symptoms. But, I’m obviously intolerant to carbohydrates of any kind. I’d say the first C-Peptide test seemed much more logical.
Answer:
You ask very good questions. It should be noted that those high anti-GAD antibody levels are considered markers for type 1 diabetes. When they occur in people who have what appear to be type 2 diabetes, it may be supportive evidence for latent-onset autoimmune diabetes of adulthood (also known as LADA). This is the formal name given to latent type 1 diabetes. It is true that the C-Peptide levels eventually go to very low levels, but this may take years to happen. In the meantime, you are in a compensated form of diabetes. You do have some insulin secretion. However, this may continue to fall over time. It also makes a difference when you get the C-Peptide measured. What it fasting or post-meal? The post-meal C-Peptide would be expected to be higher and help discriminate more as your blood sugar rises during this time. The C-peptide may have improved, in your case, after a period of time of improved blood sugar control. This phenomenon is called glucotoxicity. Anything that improves blood sugars will make the remaining beta cells work better. In conclusion, the answer is still not conclusive. The most important thing is that you continue to maximize your blood sugar treatment.
JTL