Incident dysglycemia and progression to type 1 diabetes among participants in the Diabetes Prevention Trial-Type 1

Abstract

Objective: We studied the incidence of dysglycemia and its prediction of the development of type 1 diabetes in islet cell autoantibody (ICA)-positive individuals. In addition, we assessed whether dysglycemia was sustained.

Research design and methods: Participants (n = 515) in the Diabetes Prevention Trial-Type 1 (DPT-1) with normal glucose tolerance who underwent periodic oral glucose tolerance tests (OGTTs) were followed for incident dysglycemia (impaired fasting glucose, impaired glucose tolerance, and/or high glucose levels at intermediate time points of OGTTs). Incident dysglycemia at the 6-month visit was assessed for type 1 diabetes prediction.

Results: Of 515 participants with a normal baseline OGTT, 310 (60%) had at least one episode of dysglycemia over a maximum follow-up of 7 years. Dysglycemia at the 6-month visit was highly predictive of the development of type 1 diabetes, both in those aged <13 years (P < 0.001) and those aged > or =13 years (P < 0.01). Those aged <13 years with dysglycemia at the 6-month visit had a high cumulative incidence (94% estimate by 5 years). Among those who developed type 1 diabetes after a dysglycemic OGTT and who had at least two OGTTs after the dysglycemic OGTT, 33 of 64 (52%) reverted back to a normal OGTT. However, 26 (79%) of the 33 then had another dysglycemic OGTT before diagnosis.

Conclusions: ICA-positive individuals with normal glucose tolerance had a high incidence of dysglycemia. Incident dysglycemia in those who are ICA positive is strongly predictive of type 1 diabetes. Children with incident dysglycemia have an especially high risk. Fluctuations in and out of the dysglycemic state are not uncommon before the onset of type 1 diabetes.

Figure 1

Shown are cumulative incidence curves for the subsequent development of type 1 diabetes according to whether dysglycemia occurred at the 6-month visit. The actual proportion of those developing type 1 diabetes is shown for each curve. The cumulative incidence was significantly greater when dysglycemia occurred at the 6-month visit.

Figure 2

Shown are cumulative incidence curves for the development of type 1 diabetes according to whether participants were aged <13 or ≥13 years among those who were dysglycemic at the 6-month visit. The cumulative incidence was significantly higher in the younger age-group, with an estimate of 94% by 5 years in those children.