Correlation between Total Solar Irradiance and Glycated Hemoglobin 2 to 3 Months Later in Patients with Diabetes: A Big-Data Analysis.

OBJECTIVES: Much attention has been paid recently to a relationship between glucose metabolism and weather. This study investigated the temporal correlation between total solar irradiance (TSI) and glycated hemoglobin (A1C) values in patients with diabetes.

METHODS: In 1531 patients with diabetes who received follow-up care between 2009 and 2013 (type 1 diabetes, 123 patients; type 2 diabetes, 1408 patients; male 53.6%; mean age, 61.2 years), A1C levels were measured a total of 58,830 times. The correlation between mean monthly TSI and mean A1C values from 1 to 4 months later was then examined.

RESULTS: The mean values for TSI and A1C throughout the entire study period were 13.7 MJ/m(2) and 7.7%, respectively. The correlation coefficient between TSI and mean monthly A1C values at 1 to 4 months was -0.516, -0.734, -0.726 and -0.475, respectively (all p<0.001).

CONCLUSIONS: There was a highly negative correlation between TSI and mean A1C values 2 to 3 months later in this population; thus, this fact may need to be considered when using A1C levels as a glycemic control index in patients with diabetes. Further studies are warranted.