I’ve had people tell me a type 2 diabetic can become a type 1. I was quite sure that was not true. Can you please clarify?

This question raises an ongoing debate about the imprecision of the nomenclature used to describe diabetes. Type 1 diabetes is thought to be a disease involving immune-mediated destruction of the insulin-producing cells in the pancreas, the beta cells. The usual course is for onset before age 30, in thin people, often presenting with the stormy illness of diabetic ketoacidosis and, less frequently, running in families. On the other hand, type 2 diabetes has a major component of insulin resistance, is associated with obesity, age over 40, and has a frequent family history. Most patients have a gradual onset of the disease in that they do not develop diabetic ketoacidosis. As we apply new tools such as C-peptide measurement, anti-GAD antibodies, and study patients before the frank onset of symptoms, it has become apparent that these nice categories do not fit all patients. We have some people with diabetes in the slot between 25 to 40 years of age where it is not clear which type of diabetes they have. Some have early type 2 diabetes and some have late-onset type 1 diabetes, although it is not altogether obvious at the time of diagnosis. It is not true that type 2 diabetes somehow morphs into type 1 diabetes. Some may be misclassified. Some with type 2 diabetes go on to lose a significant amount of insulin secretion and require insulin. This might be misclassified as someone who had type 2 diabetes go into type 1 diabetes. This debate will continue. The most important point of all is that blood sugar control is the most important outcome.

JTL