Seasonal and decadal changes in glycated albumin levels of Japanese blood donors

BackgroundThe Japanese Red Cross Society measures levels of glycated albumin (GA), an indicator of mean blood glucose levels, in blood obtained from all donors.MethodsChanges in mean GA levels and the percentage of cases of prediabetes from 2009 to 2018 were investigated in approximately 4.2 million, healthy, first-time blood donors aged 16-64 years, and the seasonal characteristics of GA and the association of the GA level with body mass index (BMI) were clarified.ResultsMean GA levels decreased over the decade, with a decrease of 0.42-0.77% in male and 0.39-0.49% in female donors in the groups categorised by age. The percentage of prediabetes cases also decreased over the decade, with the largest decrease in those in their 60s. GA levels were higher in the warm season than in the cold season. In 2018, the seasonal difference in the GA level was 0.48% (95% confidence interval [CI] 0.45-0.50%) for male and 0.45% (95% CI 0.41-0.48%) for female donors. GA had a linear negative correlation with BMI in the younger generation. A trend of increasing GA with BMI was noted in those in their 30s and older.ConclusionsMean GA levels and the percentage of prediabetic cases have decreased, possibly resulting from public health promotion efforts and early diagnosis of diabetes mellitus. The present data on GA seasonal variation, showing higher levels in the warm season, and the association between BMI and GA may be useful for clinical practice.