Mean HbA1c, variability and mortality in older people with diabetes

By Colin Kenny, Editor – Diabetes Distilled
 
Glycaemic targets for people with diabetes in later life should be optimised and individualised, as more stringent targets can be associated with increased mortality. Investigators wanted to assess the association between glycaemic control and the variability of HbA_1c over time, and how this impacts on mortality in older people with diabetes. They found that both low and high levels of HbA_1c led to an increased mortality risk, and the degree of variability also seemed to be an important factor, suggesting that a stable glycaemic level in the middle range is associated with a lower mortality risk.
 
Investigators used data from 587 UK primary care practices in The Health Improvement Network database. They included patients of either sex who were 70 years and older with type 1 or type 2 diabetes. The primary outcome was time to all-cause mortality. The cohort consisted of 54,803 people, of whom 17,680 (8614 [30.7%] women and 9066 [33.8%] men) died during the observation period.
 
The data showed a J-shaped distribution for mortality risk in both sexes, with significant increases with HbA_1c values greater than 8% (64 mmol/mol) and less than 6% (42 mmol/mol). The researchers assigned a score to glycaemic variability and those with a higher score also had excess mortality, especially when they also had a high HbA_1c. They concluded that both low and high levels of HbA_1c were associated with an increased mortality risk, and that the level of variability also seemed to be an important factor.
 
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