Rapid Deterioration in Type 2 Diabetes: Rethink the Diagnosis

Hello. I'm Dr Charles Vega, and I am a clinical professor of family medicine at the University of California at Irvine. Welcome to Medscape Morning Report, our 1-minute news story for primary care.

Onset of type 1 diabetes after age 30 is common. But given that the overwhelming majority of adults with new-onset diabetes will have type 2, perhaps we can be forgiven for often misdiagnosing type 1 patients at presentation. Previous research has found that type 1 diabetes is nearly as likely to occur after the age of 30 as it is in younger people.

Recognizing adult-onset type 1 diabetes at presentation can be like trying to pick out a needle in a haystack. The prevalence of overweight and obesity is as high among people with type 1 diabetes as in the general population, making it even more difficult to identify these patients.

This current study involved 600 adults with diabetes who were diagnosed in a primary care practice. Type 1 diabetes was eventually identified in 20% of this group.

One key sign identified from this study is rapid deterioration in glycemic control despite the use of oral glucose-lowering medications. Rapid insulin requirement was highly predictive of late-onset type 1 diabetes, with 84% requiring insulin within 1 year. Over half developed severe endogenous insulin deficiency consistent with type 1 diabetes, but 47% of patients with severe insulin insufficiency claimed that they had type 2 diabetes.

Compared with the group with younger-onset type 1 diabetes, this older-onset group was similar in terms of body mass index (BMI), autoantibody positivity, and genetic risk scores. In contrast, they differed markedly from those with type 2 diabetes diagnosed after age 30 years, with lower average BMIs, a higher likelihood of positive islet autoantibody tests, and higher type 1 diabetes genetic risk scores.

Adult-onset type 1 diabetes patients shouldn't have to wait for ketoacidosis to be recognized. If a patient with presumptive type 2 diabetes deteriorates despite good adherence to aggressive oral treatment, rethink the diagnosis.