Orsi E, et al. - Authors attempted to estimate various measures of haemoglobin (Hb) A1c variability, compared with average HbA1c, as independent predictors of mortality in patients with type 2 diabetes. The inference drawn was that HbA1c variability served as a strong, independent predictor of all-cause mortality in type 2 diabetes. It was found to be even more powerful compared to average HbA1c in predicting mortality.

Methods

• A total of 15,733 patients with type 2 diabetes from 19 diabetes clinics were recruited in the Renal Insufficiency And Cardiovascular Events Italian multicentre study during 2006-2008.
• A total of 3 to 5 HbA1c measures, obtained during the 2-year period before enrolment, were available from 9 centres (8,290 patients).
• These aided in estimating the average HbA1c (HbA1c -MEAN) and HbA1c variability, measured as intra-individual standard deviation (HbA1c-SD), SD adjusted for the number of HbA1c assessments (HbA1c-AdjSD) and coefficient of variation (HbA1c-CV), the HbA1c-SD to HbA1c-MEAN ratio.
• Vital status on October 31, 2015 was obtained for 8,252 patients (99.5%).

Results

• A rise was noted in the measures of HbA1c variability based on the quartiles of HbA1c-MEAN and vice versa.
• Data shed light on the connection between HbA1c-MEAN and measures of HbA1c variability with all-cause mortality.
• Nonetheless, lower strength of association of HbA1c-MEAN was discovered compared to that of HbA1c-SD, HbA1c-CV or HbA1c-AdjSD, and disappeared after adjusting for confounders and any of the measures of HbA1c variability.
• Findings disclosed that the mortality increased with quartiles of HbA1c-MEAN, HbA1c -SD, HbA1c-CV and HbA1c-AdjSD, but only the association with HbA1c variability measures remained after adjustment for confounders and/or each other measure.
• In the fully adjusted model, mortality risk was found to be lower for HbA1c-SD below the median and higher for HbA1c-SD above the median, irrespective of whether HbA1c-MEAN was below or above the median.