HbA1c and systolic blood pressure variation to predict all-cause mortality in patients with type 2 diabetes mellitus

Background

Glycated hemoglobin A1c (HbA1c) variation or blood pressure (BP) variation was known to be an independent predictor of all-cause mortality in patients with type 2 diabetes mellitus (T2DM). This study aimed to investigate the combined effect of HbA1c and systolic blood pressure (SBP) variation on all-cause mortality and if there was a gender difference in patients with T2DM.

Methods

Patients with T2DM who had at least three HbA1c, SBP measurements within 12–24 months during 2001–2007 were included. Coefficient of variation (CV) was used to evaluate variation. The 75th percentile of HbA1c-CV and SBP-CV were set as a cutoff to define high and low variation. Hazard ratios (HRs) and 95% confidence intervals were estimated using Cox proportional hazard models.

Results

A total of 2744 patients were included, of whom 769 died during the 11.7 observation years. The associated risk of all-cause mortality was 1.22 [1.01- 1.48], P = 0.044, for low HbA1c-CV & high SBP-CV; 1.28 [1.04–1.57], P = 0.020, for high HbA1c-CV & low SBP-CV; and 1.68 [1.31–2.17], P < 0.001, for high HbA1c-CV & high SBP-CV. The associated risk remained unchanged in either males or females older than 50 years old, although there is only numerically higher for high HbA1c-CV & low SBP-CV in females older than 50 years old.

Conclusions

Both HbA1c and SBP variation were significant predictors of all-cause mortality in patients with T2DM. The combined effect was higher than either alone and no gender difference in patients older than 50 years old.