medwireNews: The effect of glycemic control on all‐cause mortality risk depends on diabetes duration in people aged 65 years and older with type 2 diabetes, study findings indicate.
Jonas Nielsen (Copenhagen University Hospital, Denmark) and colleagues report that “strict glycaemic control was associated with an increased risk of death among individuals with long (>5 years) diabetes duration,” whereas for those with a shorter diabetes duration “strict glycaemic control was associated with the lowest risk of death.”
The study, published in Diabetes, Obesity and Metabolism, included primary care data for 9734 individuals age 65 years and older (median 73.5 years) with type 2 diabetes who had three successive annual glycated hemoglobin (HbA1c) measurements taken between 2005 and 2013.
Almost two-thirds (62.4%) of participants had had diabetes for 5 or more years, and these people were older, more often prescribed sulfonylureas and insulin, and more likely to have severe comorbidities such as late diabetic complications and cardiovascular disease than those with a shorter duration of diabetes.
During a median 7.3 years of follow-up, 3320 participants died.
After adjustment for age, sex, medication use, and comorbidity, the researchers found that the risk for death generally increased with increasing HbA1c among individuals who had a diabetes duration of less than 5 years (median 2.3 years).
Specifically, people with mean baseline HbA1c levels of 7.0–7.9% (53–63 mmol/mol), 8.0–8.9% (64–74 mmol/mol), and 9.0% or higher (≥75 mmol/mol) had significant 26%, 50%, and 45% higher risks for death, respectively, than those with a mean baseline HbA1c level below 6.5% (<48 mmol/mol).
By comparison, the risk for death followed a J-shaped curve among the individuals with a diabetes duration of 5 years or more (median 9.3 years). In this group, individuals with the lowest mean HbA1c levels (<6.5%) had a significant 21% increased risk for death relative to those with a mean level of 7.0–7.9%. The risk was also significantly increased for people with mean HbA1c levels of 8.0–8.9% and 9.0% or higher, by 32% and 60%, respectively.
The researchers observed a similar pattern for 5‐year absolute risks for all‐cause mortality, as well as across subgroups defined by age, sex, and degree of comorbidity.
Nielsen et al conclude: “Although our study does not allow for causal inference due to its observational design, our results suggest that aiming for normoglycemic levels in those with short duration of diabetes may be beneficial, whereas for individuals with long diabetes duration, setting universal goals may be less straight-forward.
“In these patients, additional important factors, such as frailty, life expectancy and patient preferences should be considered, to better provide patient-centered care that balances the pros and cons of tight glycemic control.”
By Laura Cowen
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Diabet Obes Metab 2019; doi:10.1111/dom.13891