My 24-year-old daughter saw her general practitioner on Tuesday, with a complaint of constant thirst and unexplained weight loss. The doctor did blood work and her glucose was 503 mg/dl [27.9 mmol/L]. He set her up with and endocrinologist and gave her Avandaryl. She saw the endocrinologist today. They pricked her finger and said her glucose was 300 mg/dl [16.7 mmol/L]. He said he thought she had type 2, but was going to treat her for type 1. He said to test her blood before each meal and give herself the appropriate amount of insulin, as well as a dose of insulin before bed. He did no other tests on her.

My daughter is confused. If he thinks it’s type 2, why treat her for type 1? Is there a test to determine which type of diabetes she has?

She wants to go see another endocrinologist, but doesn’t know if she should follow this doctor’s instruction or wait until she can get into another doctor. What should she do?

The endocrinologist may have had all the appropriate laboratory work completed by your daughter’s primary physician. It is common to treat newly-diagnosed patients with very high blood sugars with insulin, especially in the age range where there is an overlap between type 1 and type 2 diabetes. If she really has type 1 diabetes, oral agents will not work and she won’t get any better after feeling ill for all that time. If she has type 2 diabetes, her blood sugars will still come down. It usually becomes obvious if she will need a lot less insulin after a short time on the insulin. If she has type 2 diabetes, she can be easily transferred to an oral agent with better immediate response than if she were initiated at the time her blood sugars were very high. It also gives the doctor additional time for any further testing to be completed. Some tests that are done to separate out type 1 from type 2 diabetes include measuring antibodies directed against the insulin-producing cells. You may recognize these as anti-GAD antibodies, anti-islet antibodies, anti-ICA antibodies, or anti-insulin antibodies. If positive, they can suggest type 1 diabetes. Additional, other tests of insulin secretion can be measured, such as C-Peptide levels. High levels suggest type 2 diabetes. Low levels suggest type 1 diabetes. It also might be possible that your daughter’s endocrinologist may be waiting to do testing when the blood sugars fall to more normal levels. In any case, I do not think you can go wrong with insulin treatment up front “until the dust settles” and it becomes more clear what type of diabetes your daughter has.

JTL