Large HbA1c changes, variability linked to HF risk in type 2 diabetes
medwireNews: Large increases or decreases in glycated hemoglobin (HbA1c) and a high degree of variability are associated with an increased risk for heart failure (HF) among people with type 2 diabetes, shows a secondary analysis of ACCORD trial data.
Ambarish Pandey (University of Texas Southwestern Medical Center, Dallas, USA) and co-investigators say their findings “highlight the importance of long-term variability in HbA1c to identify individuals with [type 2 diabetes] and adequate glycemic control who are at high risk for developing HF.”
The analysis included 8576 ACCORD participants with no previous history of HF who had HbA1c variability assessed from 8 months after enrollment – to allow for stabilization after assignment to intensive or standard glycemic control – until 3 years of follow-up.
At baseline, mean HbA1c was 8.3% (67.0 mmol/mol) while average successive variability (ASV; average absolute difference between successive values) was 0.6% at the end of the monitoring period.
During a median 6.4 years of additional follow-up, 388 participants were hospitalized for, or died due to, HF.
The researchers report in Diabetes Care that there was an approximately U-shaped association between change in HbA1c and HF risk. Specifically, individuals with a 10% or greater increase in HbA1c had a 1.55-fold higher risk for HF than those with a smaller HbA1c change while those with a 10% or greater decrease in HbA1c had a significant 1.32-fold higher risk for HF after adjustment for baseline and longitudinal changes in risk factors on follow-up.
However, Pandey and co-authors note that the risk was attenuated among the individuals with a 10% or greater decrease in HbA1c when those with a hypoglycemic event during follow-up were excluded.
This suggests that “the higher risk of HF observed among individuals with a substantial decrease in HbA1c on follow-up was largely related to downstream hypoglycemic events,” they remark.
The team also found that greater variability in HbA1c was associated with HF, with each standard deviation (SD) increase in ASV associated with a significant 34% increase in HF risk. The risk increases were 33% and 35%, respectively, when the coefficient of variation and standard deviation were instead used as measures of HbA1c variability.
The authors conclude: “Future studies are needed to determine whether glycemic variability may meaningfully inform glucose control strategies in patients with [type 2 diabetes] to prevent HF.
They add: “These findings are particularly relevant since the newer antihyperglycemic therapies such as sodium–glucose cotransporter 2 […] inhibitors, which are associated with reduction in the risk of incident HF, have been shown to lower glycemic variability.”
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