[One-year variability of HbA1c in children and adolescents with type 1 diabetes - preliminary results].

INTRODUCTION

The glycated A1c hemoglobin (HbA(1)c) is an accepted marker of glycemic control in patients with type 1 diabetes (T1DM) and a predictor of long-term microvascular diabetic complications. There have been reports of seasonal fluctuations of HbA(1)c levels in type 1 and type 2 diabetic patients of different age.

AIM OF THE STUDY

The aim of the study was to investigate retrospectively investigate seasonal variations of HbA(1)c levels in a pediatric population of T1DM patients over a one-year period.

MATERIALS AND METHODS

The study group included 473 patients aged 2.4 -18 years (mean 13.3 ± 3.7) with T1DM duration of at least 6 months in whom HbA(1) c levels were tested between November 1, 2008 and October 31, 2009. HbA(1)c was measured by high performance liquid chromatography (HPLC).

RESULTS

The total number of 1417 HbA(1)c tests were performed (mean 3.0 tests/patient/year). Mean HbA(1)c level was (mean ± SD) 7.7 ± 1.5% (range 5.2 -15.7%; median 7.4%; 25-75% range: 6.7 -8.2%). Statistically significant differences in monthly HbA(1)c levels were found (analysis of variance; p < 0.001). The lowest HbA(1)c levels, observed in August and September, were significantly lower than in February, March, April and December. Relative HbA(1)c levels, expressed as percentages of individual patient's mean value for twelve months, showed similar seasonal fluctuations: the lowest values were observed in August and September and the highest were noted in February, March, April, November and December.

CONCLUSIONS

1. HbA(1)c levels in young T1DM patients show seasonal variability. 2. Considering seasonal HbA(1)c fluctuations in patients education and management schedules could improve glycemic control. 3. Seasonal changes of HbA(1)c levels should be considered in short-term(lasting several months) clinical study designs.