June 26, 2005
Diagnosis and Symptoms
Question from Nova Scotia, Canada:
I was diagnosed with type 1 when I was 37 after being very sick for over a year. Because of my age, they first treated me as type 2, but I continued to lose more weight and my lowest fasting blood sugar was 11 mmol/L [198 mg/dl]. My endocrinologist decided I was type 1 and put me on insulin. This new specialist that I've been seeing for two months tested for antibodies and advised me that I am actually a type 2 diabetic. He has also prescribed Avandamet, twice a day, along with my insulin. Is it that this blood test has just been available over the past few years to actually diagnose or what? I am just totally confused, disheartened. This "younger" endocrinologist is extremely busy and I felt that he just didn't give me the time to explain my feelings and especially my questions and concerns. Any insight you can give me is appreciated! By the way, I was never overweight. Before my initial diagnosis, I weighed 142 pounds. Now, I am up to 175 pounds, even though I go to the gym three times a week.
The nomenclature for defining the types of diabetes mellitus are simply inadequate. As a result, over the past five years, we have individuals in all these gray areas trying to determine what type of diabetes they have. In your case, traditional thought would have suggested you have type 2 diabetes but your initial physician thought you had type 1 diabetes. Type 2 diabetes is associated with both insulin resistance and inadequate insulin secretion. Type 1 diabetes is associated with the immune destruction of insulin-producing cells and an absolute deficiency of insulin.
Previously, people with type 2 diabetes were over 40, obese, and had a family history. People with type 1 diabetes were thin, did not necessarily have a family history, and were usually less than 30. What about people between the ages of 30 to 40? This requires physicians to use a combination of laboratory tests and clinical parameters to make the best diagnosis. This includes family history, age of onset, presence of obesity, presence of insulin secretion in response to test meal or condition as tested by C-peptide levels, and the measurement of antibodies, including anti-GAD antibodies. The latter are used because they are most often positive for the longest time following diagnosis. Other antibody tests may have been positive but revert to normal over time. So, you see, a positive test is helpful, but a negative test does not rule out type 1 diabetes. Your physician must use all the above information to determine the type of diabetes and your response to treatment is especially important. If you respond well to the oral agents, it is more likely you have type 2 diabetes.