HbA1c can be a useful glycemic control marker for patients with neonatal diabetes mellitus older than 20 weeks of age.

Abstract Background The accuracy of most HbA1c analysis methods is affected by the presence of increased fetal hemoglobin (HbF). The objective of this study was to investigate the age at which HbA1c measurements become useful for monitoring glycemic control in patients with neonatal diabetes mellitus (NDM). Methods We retrospectively analyzed the data of 5 NDM patients diagnosed at 38 ± 20 days of age, who each had several available HbA1c measurements during the first year of life, with a control group of HbA1c values over the course of 1 year for 13 patients with type 1 diabetes mellitus (T1DM). Mean blood glucose (MBG) levels derived from premeal or premeal plus bedtime blood glucose measurements prior to HbA1c measurements were compared to HbA1c values. Results The NDM patients' age at which the difference in the HbA1c/MBG ratios became not significant between the NDM patients and the T1DM patients was 21 weeks of age and over. Even after the HbA1c was adjusted for HbF, this ratio was significantly lower in the NDM patients at Conclusions HbA1c can be a useful glycemic control marker for NDM patients > 20 weeks of age.