The Frequency and Determinants of HbA1c Variability in Type 2 Diabetic Patients

Aim: Glycated hemoglobin (HbA1c) is an efficient and easy test to evaluate glycemic control of patients with type 2 diabetes (T2DM). This study aims to evaluate HbA1c variability and associated factors in patients with T2DM. Methods: Four hundred four consecutive patients with T2DM who gave consent to participate and who were eligible were included. The inclusion criterion was presence of three or more HbA1c levels in 1 year. A change ≥0.5% in HbA1c was identified as a significant variability in HbA1c in 1 year. Primary endpoint of the study was to identify the factors associated with HbA1c variability. Patients were grouped as (1) without variability, (2) one variability, and (3) more than one variability. Variability frequency and associated factors such as body mass index, smoking, and c-peptide value were assessed. Results: There were 404 patients (45.3% male) with mean age 58.91 ± 10.8 years. Thirty-four patients (8.4%) had no variability, 19 patients (4.7%) had one variability, and 351 patients (86.9%) had more than one variability. Patients only on insulin treatment and patients on both oral antidiabetic agents (OAD) and insulin had higher variability than patients only on OAD (P = 0.002; P < 0.01). Patients with variability had higher HbA1c levels than patients without variability (P < 0.01). A 1% increase in HbA1c had a 4.864-fold (95% confidence interval: 2.360-10.023) increased variability risk. Conclusions: HbA1c variability is seen in 9 of 10 patients with T2DM and higher HbA1c values and poor glycemic control are associated with a higher risk of HbA1c variability.