Clinical characteristics in Japanese children with nonobese type 2 diabetes

It is well known that the incidence of youth-onset type 2 diabetes is increasing worldwide. On the other hand, most studies have shown that the majority of youth-onset type 2 diabetes occurs in obese individuals, generally with a body mass index (BMI) greater than the 90th or 95th centile for sex- and age-matched children and adolescents. However, we identified some Japanese children with nonobese type 2 diabetes and BMI less than 90th centile by a urine glucose screening program at schools in the Tokyo Metropolitan Area. According to the results obtained from the screening, clinical characteristics of patients with nonobese type 2 diabetes seemed to be different from those in obese type 2 diabetes. Nonobese patients tended to show lower insulin secretion abilities and milder, but evident, insulin resistance from the time of diagnosis. Female, low birth weight (small for gestational age), and genetic background, not related to β-cell-associated autoimmunity, may play a role in development of nonobese type 2 diabetes. In addition, nonobese patients tend to progress earlier to pharmacological treatment including oral hypoglycemic drugs and insulin. Further studies are needed to confirm to these findings and clarify the pathophysiology of children with nonobese type 2 diabetes.