Increasing HbA_1c levels predict the onset of type 1 diabetes in high-risk children

Stene LC et al. (2006) Normal but increasing hemoglobin A1c levels predict progression from islet autoimmunity to overt type 1 diabetes: Diabetes Autoimmunity Study in the Young (DAISY). Pediatr Diabetes 7: 247–253

Currently, there is no method to predict the onset of type 1 diabetes (T1D). Stene and colleagues investigated the efficacy of glycated hemoglobin (HbA_1c) level (which can predict onset of type 2 diabetes) as a predictor of progression from islet autoimmunity to overt T1D.

The authors enrolled 92 children (mean age 4.8 years) who carried human leukocyte antigen genotypes associated with T1D or had first-degree relatives with T1D, and were positive for at least one islet autoantibody on at least two consecutive clinic visits. In total, 28 children developed T1D, at a median age of 6.5 years; 75% of these had first-degree relatives with the disease. Children who went on to develop T1D were slightly younger and had autoantibodies against a significantly higher number of islet antigens than children who did not (P = 0.008), although both groups had similar initial plasma glucose and HbA_1c levels. Each increase of 1 SD (0.4%) in HbA_1c levels was associated with a fivefold increase in the risk of progression to T1D. By contrast, each increase of 1 SD (1.1 mmol/l) in random plasma glucose levels resulted in only a slight (1.4-fold) increase in the risk of progression to T1D.

The authors conclude that rising HbA_1c levels (even within the normal range) over time indicate progressive disruption of glucose regulation, and accurately predict the onset of T1D in high-risk children.