Prediabetes a poor predictor of outcomes in older adults
medwireNews: Adults who develop prediabetes when older than 70 years are more likely to regress to normoglycemia or die of other causes than to progress to type 2 diabetes, research shows.
In a commentary linked to the publication in JAMA Internal Medicine, Kenneth Lam and Sei Lee, both from the University of California in San Francisco, USA, suggest that prediabetes “can safely be ignored” in this age group, which already has a high treatment burden.
“Guidelines should clarify that prediabetes is a concept that should be reserved for healthier, middle-aged adults rather than older adults with frailty,” they write, noting that for these people “the current recommendations for annual monitoring and weight loss are likely low yield.”
Mary Rooney (Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA) and co-workers studied 3412 participants of the Atherosclerosis Risk in Communities study who were an average age of 75.6 years at the time of blood glucose measurement.
In all, 73% of those without a previous diabetes diagnosis had prediabetes, when this was defined as having either glycated hemoglobin (HbA1c) levels of 5.7–6.4% (39–46 mmol/mol) or impaired fasting glucose levels of 100–125 mg/dL (5.6–6.9 mmol/L).
The prevalence was 44% and 59% when defined only according to HbA1c or impaired fasting glucose, respectively, and 29% of people met both definitions.
During a median 5 years after these diagnoses were made, just 9% of people with HbA1c-defined prediabetes progressed to type 2 diabetes, while 13% regressed to normal glucose levels, 19% died, and the large majority (59%) remained with prediabetic glucose levels. In addition, 3% of people with normal HbA1c at baseline progressed to type 2 diabetes.
Progression from prediabetes to diabetes was significantly more common in Black than White people, at 11% versus 8%, but did not differ with age group or sex. Rates of diabetes diagnosis during follow-up were also higher in people who had prediabetes based on HbA1c plus impaired fasting glucose, rather than just one of these criteria.
However, the risk for all-cause mortality did not significantly differ between people with normal glucose levels or prediabetes at baseline, regardless of the definition used, report the researchers.
In their commentary, Lam and Lee note that the majority of symptoms related to type 2 diabetes occur as a result of end-organ damage, and only after many years of living with high glucose levels.
“Therefore, the modern definition of diabetes is conceptually closer to being a risk factor itself (eg, something that portends future disease) than an illness (eg, something that patients experience),” they write.
“Prediabetes, then, is a risk factor twice removed; it is a risk factor for diabetes, which itself may be most accurately described as a risk factor for end-organ vascular disease.”
The commentators say the findings may also have implications for diabetes diagnosis in this older age group, suggesting there may be a high rate of reversion, particularly among those with glucose levels only mildly above the diagnostic threshold, and a low risk for poor outcomes.
Given this, they conclude that “shifting the cutoffs for diagnosing diabetes in older adults would help us focus treatment on those older adults for whom diabetes is likely to result in symptomatic end-organ damage, while avoiding identifying many older adults for whom diabetes is unlikely to cause harm.”
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