Difference of seasonal variation between glycated albumin and glycated haemoglobin

Background: Glycated albumin reflects 2-3-week glycaemic controls, and in addition to glycated haemoglobin, it has been used as a glycaemic control indicator. We presumed that glycated albumin also has seasonal variations and is related to temperature, similar to glycated haemoglobin. Methods: The subjects were diabetic outpatients from April 2007 to March 2013. This resulted in the enrolment of 2246 subjects and the collection of a total of 53,968 measurements. Mean glycated haemoglobin, glycated albumin, and plasma glucose were calculated for each month over six years. The associations of the measures with each other and the average temperature for each month in Tokyo were assessed using Spearman rank correlation coefficients. Results: Plasma glucose was highest in January and lowest in May. Glycated haemoglobin was highest in March and lowest in September. Glycated albumin was highest in May and lowest in December. Glycated albumin tended to have a disjunction with plasma glucose in winter. Glycated haemoglobin had seasonal variation, but glycated albumin did not. Plasma glucose and glycated haemoglobin showed significant negative correlations with temperature (rs= -0.359, P < 0.001, rs= -0.449, P < 0.001, respectively), but glycated albumin did not. However, glycated albumin was inter- correlated with plasma glucose (rs= 0.396, P < 0.001) and glycated haemoglobin (rs= 0.685, P < 0.001), and glycated haemoglobin was inter-correlated with plasma glucose (rs= 0.465, P < 0.001). Conclusion: Glycated albumin and glycated haemoglobin showed different seasonal variations from each other over the six-year study period. Thus, further studies to identify factors that contribute to glycated albumin are needed.