Visit-to-visit glycaemic variability tied to cardiovascular risk in T2DM patients

Higher visit-to-visit glycaemic variability (VVV) seems to increase the risk of cardiovascular events in patients with type 2 diabetes mellitus (T2DM), a new Japan study has found. Such an interaction is independent of mean glycated haemoglobin (HbA1c) levels.

The researchers enrolled 4,532 T2DM patients from the EMPATHY trial who had at least three available HbA1c measurements. VVV was quantified using the coefficient of variation in HbA1c (CV-HbA1c). The main outcome of interest was a composite of cardiovascular endpoints, including vascular, cardiac, renal, and cerebral events.

Over a median follow-up of 38 months, 190 participants developed cardiovascular events, and its cumulative incidence rate grew significantly with increasing levels of CV-HbA1c (p=0.01 for linear trend test). Adjusting for confounders—such as sex and age, smoking, disease duration, estimated glomerular filtration rate, and comorbidities—did not attenuate this interaction.

To confirm these findings, the researchers divided participants into quintiles of CV-HbA1c and performed logistic regression analysis.

They found that those in the fourth (adjusted odds ratio [OR], 2.15, 95 percent confidence interval [CI], 1.33–3,47; p=0.002) and fifth (adjusted OR, 1.98, 95 percent CI, 1.22–3.24; p=0.006) quintiles were around twice as likely to experience cardiovascular events than comparators in the bottom quintile. Adjusting for mean HbA1c left the risk estimates almost unchanged.

Subgroup analysis showed that the interaction between cardiovascular events and CV-HbA1c was stronger in participants with mean HbA1c levels <7 percent. Heterogeneity with respect to other subgroups was not significant.

“The present findings suggest that the long-term variability of HbA1c as well as mean HbA1c is an important glycaemic indicator in the management of patients with T2DM, especially in those with mean HbA1c <7 percent,” the researchers said.