HbA1c variability linked to serious infections

Fluctuations in HbA1c levels in between clinic visits may put individuals with type 2 diabetes (T2D) at increased risk of serious infections, according to a study.

For the study, the Clinical Practice Research Datalink was used. The total population comprised 411,963 adult T2D patients in England, with each having at least four HbA1c measurements recorded during a median follow-up period of 6 years. The median gap between measurements was 198 days.

Researchers conducted Poisson regression to estimate the incidence of infections requiring hospitalization in relation to HbA1c variability score and average level. Attributable risk fractions (AF) were calculated using reference categories for variability (HbA1c variability score <20) and average level (42–48 mmol/mol).

The average HbA1c level of the population was 58.0 mmol/mol, and 38.3 percent of patients had a HbA1c variability score (HVS) of at least 50, which indicated that at least half of their measurements during the study period varied by 10 percent or greater relative to the previous measurement.

Even modest HbA1c variability (variability score ≥20, 73 percent of patients) showed an association with increased infection risk (incidence rate ratio [IRR] >1.2) but only at higher average levels (≥64 mmol/mol, 27 percent of patients). Estimated attributable risk fractions were notably greater for variability than average level (17.1 percent vs 4.1 percent).

The association between HbA1c variability and infection risk was pronounced among older patients.