Seasonal variability of glycated hemoglobin in a diabetic population from southern Europe

Abstract

Aims: To analyze the seasonal variations in A1c levels among a southern European diabetic population.

Methods: We examined all monthly-grouped A1c determinations from diabetic patients during the period 2006-2011, in a region of southern Spain.

Results: There were 61,329 records available. The mean A1c value was 56mmol/mol (7.2%±1.7%) (95% CI, 55-56mmol/mol (7.2%-7.3%), with a range of 0.2%. The highest value was in February and the lowest in July (56mmol/mol (7.3%) and 54mmol/mol (7.1%), respectively) (P<0.01). However, spectral analysis and correlation coefficients did not reach significance, and the series presented no seasonal pattern.

Conclusions: In our area, although the A1C levels have some monthly fluctuation they show no significant seasonal pattern. Thus, the seasonal fluctuation of HbA1c is not a limitation for decision making in clinical practice.

Keywords: Diabetic population; Glycated hemoglobin; Seasonal variability.