Dr. Roach: Lab results signify prompt treatment for Type 1 diabetes

Dear Dr. Roach: I was recently diagnosed with Type 1 diabetes at the age of 62. My mother was diagnosed with Type 1 diabetes at 57. My glutamic acid decarboxylase 65 (GAD65) antibody results came in at greater than 25,000 U/mL and was confirmed twice by the lab. My C-peptide level is below 1 ng/mL. My blood sugar level was 542 mg/dL, and I was immediately started on insulin.

I thought I was healthy prior to these tests, since I’m a marathon runner, high-mileage biker and hot yoga student; however, these numbers don’t seem good. I have not actually heard anything back from my new endocrinologist, so I’m assuming that they merely think the test results are wrong — or there’s nothing to be done.

— Anon.

Dear Anon.: Most people think of adult-onset diabetes as Type 2, which sometimes requires insulin, and childhood-onset diabetes as Type 1, which always requires insulin. However, the situation is more complex, and there are several other causes of diabetes.

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Type 1 diabetes is caused by the body attacking the insulin-making cells in the pancreas. You have a very high level of GAD65 antibodies, which are found in the islet cells of the pancreas, and this makes an autoimmune cause very likely. C-peptide is a smaller protein that is made on the same larger protein string as insulin. Since your C-peptide is very low, this confirms that your body is not making significant amounts of insulin, which makes the diagnosis of Type 1 diabetes essentially certain, in combination with the high level of autoantibodies.

Type 1 diabetes can appear in people of below normal, normal, or above normal weight and with any level of exercise, but late-onset Type 1 diabetes is uncommon compared to diagnoses made in childhood or adolescence. Type 1 diabetes typically presents itself more slowly in adults, so it’s likely you had the antibodies for a long time before you were diagnosed.

Treatment with insulin is effective at maintaining a near-normal blood sugar level for most people. This usually includes multiple shots per day, but an insulin pump may also be used to provide excellent control of blood sugar. A continuous glucose monitor can really help you and your doctor manage your diabetes. These are not required in people with well-controlled Type 2 diabetes, but I think they will become standard with Type 1 and in more-difficult-to-control cases of Type 2.

People with Type 1 diabetes absolutely need insulin. We have many great oral medicines for Type 2 diabetes and some non-insulin medicines that also help with Type 1 diabetes, but insulin is still a necessity. In my opinion, people with Type 1 diabetes should be managed by an endocrinologist whenever possible.

Finally, let me mention that autoimmune diseases often run together. People who get diagnosed with Type 1 diabetes at your age and have a high level of antibodies are at a high risk (30% or so) for developing other autoimmune diseases (especially of the thyroid, but also celiac disease). It may be worthwhile to get blood tests done to make an early diagnosis of celiac disease or autoimmune thyroid disease.

Readers may email questions to ToYourGoodHealth@med.cornell.edu.