medwireNews: Keeping glycated hemoglobin (HbA1c) levels within individualized target ranges over time is associated with reduced risk for mortality and cardiovascular disease (CVD) in older adults with diabetes, suggest results from an observational study.
This supports “using both a personalized approach to [HbA1c] goal setting and [HbA1c] stability over time” when treating these individuals, write Julia Prentice (Boston University School of Medicine, Massachusetts, USA) and colleagues in Diabetes Care.
They collected data from 402,043 people (mean age 76.9 years, 86.3% White, 98.8% men) with type 2 diabetes using the Veterans Affairs Boston Healthcare System and Medicare between 2004 and 2016. Of these, 52% died and 21% experienced a stroke or myocardial infarction during an average 5.5 years of follow up. Follow-up began from year 5; prior to this was the first year on record, used to determine the presence of diabetes complications and to predict life expectancy, and a 3-year baseline period with at least four HbA1c tests.
Prentice et al determined time in range (TIR) by assigning individuals to different HbA1c target ranges on the basis of life expectancy and diabetes complications; these varied from 14% of people with a target range of 6.0–7.0% (42–53 mmol/mol) to 17% with a target range of 8.0–9.0% (64–75 mmol/mol). The average baseline HbA1c was 7.0% (53 mmol/mol) and 32% of individuals had HbA1c levels in the target range for at least 40% of the time.
The researchers say that “[t]here was a graded relationship between lower [HbA1c] TIR and higher mortality and CVD outcome.” Specifically, in models controlling for covariates including mean HbA1c level and HbA1c standard deviation, individuals with TIR of 0 to less than 20%, 20 to less than 40%, 40 to less than 60%, or 60 to less than 80% had a significantly higher risk for mortality compared with those with TIR of 80–100%, at hazard ratios (HRs) of 1.22, 1.14, 1.11, and 1.10, respectively.
In the same way, individuals in these TIR groups were at significantly lower risk for CVD compared with those with TIR of 80–100%, at corresponding HRs of 1.14, 1.08, 1.07, and 1.06.
The study authors also note that other covariates such as older age, diabetes complications, and insulin use had significant relationships with mortality and CVD risk.
“Future studies may consider the influence of [HbA1c] TIR on other adverse events, such as hypoglycemia and microvascular complications, since increasing [HbA1c] variability is associated with each of these outcomes,” conclude the investigators.
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