People in the third group are obese or overweight with insulin resistance like most people with Type 2 diabetes, and they also have autoantibodies. However, they still manage to produce insulin for more than five years after diagnosis and can continue to manage their diabetes with diet, exercise, and oral medicines. It is suspected that the autoimmunity in these people is very mild.
Some researchers suggest screening anyone newly diagnosed with Type 2 diabetes for GAD antibodies. In the United Kingdom Prospective Diabetes Study (UKPDS), most study subjects with Type 2 diabetes between 35 and 45 years old who tested positive for antibodies against both GAD and islet cells progressed rapidly to insulin dependency. Some researchers have also suggested that anyone who tests positive for GAD antibodies be screened for autoantibodies to thyroid and adrenal cells, because like people with Type 1 diabetes, people with Type 1.5 diabetes seem to be at higher risk of having other autoimmune diseases.
The jury is still out on the best way to treat Type 1.5 diabetes. Maintaining tight blood glucose control may help to slow the destruction of the beta cells (and delay insulin dependency) as well as reduce the risk of diabetic complications. A few small studies suggest that insulin therapy or insulin combined with rosiglitazone (brand name Avandia) may help to preserve beta-cell function, but these results need to be confirmed in larger trials. (Using insulin in combination with rosiglitazone may increase risks for people with heart failure.)