Renal glucosuria in schoolchildren: Clinical characteristics

We conducted an annual urine glucose screening program at schools, and diagnosed schoolchildren with diabetes at an early stage of the disease. We also identified some cases of renal glucosuria (RG), based on positive urine glucose with normal glucose tolerance.

During 2000-2015, 3 309 631 schoolchildren participated in the screening program. The positive rate for glucosuria in the first test was approximately 0.1%, whereas on repeat urine test it was approximately 0.05%. In total 350 schoolchildren were positive for glucosuria on detailed examination. Oral glucose tolerance test (OGTT) was also used to evaluate glucose intolerance.

One hundred and two schoolchildren (29.7%) were diagnosed with diabetes, whereas RG was identified in 246 (70.3%) with normal glucose metabolism. In regard to the characteristics of RG, the percentage of boys was 50.3%, and the mean age at diagnosis was 11.2 ± 2.4 years. Twenty-eight children (11.4%) were overweight (body mass index standard deviation score [BMI-SDS] > +2.0 SD), whereas five (2.0%) were underweight (BMI-SDS < -2.0 SD). First-degree family history was suspected in 176 cases (71.5%). All RG subjects had normal glucose tolerance in the absence of insulin resistance and decreased insulin secretion (homeostasis model assessment for β-cell function, 78.8 ± 59.5%) on OGTT.

RG is not rare in Japanese schoolchildren with glucosuria. This disorder seems to have a strong genetic background, and to involve less growth retardation and weight loss than expected despite continuous excretion of glucose in urine.