medwireNews: Analysis of participants in the ORACL trial leads researchers to suggest that nonfrail older adults with type 1 diabetes are better off following time in range (TIR) guidance aimed at younger people.
The team found that nonfrail older adults using a sensor-augmented pump achieved a TIR “far exceeding” current recommendations for their age group, but struggled to meet the strict target for time in hypoglycemia.
“The median glucose time below range was equivalent to 29 min per day, whereas the consensus-recommended older adult glucose time-below-range target is less than 14 min per day,” say Sybil McAuley (The University of Melbourne, Victoria, Australia) and study co-authors.
Their study included data from 30 people (63% women) aged at least 60 years who used sensor-augmented insulin pumps during run-in to the ORACL closed-loop trial. These people had type 1 diabetes of at least 10 years’ duration and were already using a pump at baseline.
The run-in period provided a minimum of 10 days of continuous glucose monitor (CGM) data for all participants, during which they spent a median of 71% of their time within the recommended blood glucose range of 3.9–10.0 mmol/L (70–180 mg/dL).
Almost all (93%) participants had a TIR of at least 50%, as currently recommended for older adults, while 97% achieved the recommended less than 50% of time above 10.0 mmol/L and 73% the recommended less than 10% of time above 13.9 mmol/L (250 mg/dL).
The researchers note that the TIR target of at least 50% for older adults equates to a glycated hemoglobin target of no more than 58 mmol/mol (8.3%), which is consistent with the Diabetes UK recommended target for frail older adults.
But there was no “clinically meaningful degree of frailty” in the ORACL cohort, with 80% classed as nonfrail, 20% as pre-frail, and none as frail, and the team believes the 50% TIR target is “too lax a glycaemic target for the independent individuals without frailty who enrolled in this study.”
Just 23% of participants spent less than 1% of their time below 3.9 mmol/L, which is recommended for older adults, but again McAuley and colleagues highlight the lack of differentiation between frail and nonfrail adults.
Of note, the time spent in hypoglycemia was significantly less among the 16 participants who used predictive low glucose alerts than among the 14 who did not, at a median of 1.5% versus 2.7%, with this difference particularly marked overnight, at 0.4% versus 2.9%.
Use of predictive alerts are therefore “likely to be important for minimising hypoglycaemia,” write the researchers in The Lancet Healthy Longevity.
They also note that most hypoglycemia occurred within 4 hours after taking prandial insulin, and suggest that refining bolus dose and timing may help to reduce postprandial hypoglycemia.
Overall, the findings suggest that current TIR targets for older adults “are not suitable for cognitively healthy and functionally independent individuals without frailty,” conclude McAuley and team.
In a linked commentary, Alanna Weisman (University of Toronto, Ontario, Canada) observes that the optimal TIR target for older adults is not clear, pointing out that “[a]ll older adults with type 1 diabetes might be at an increased risk of severe hypoglycemia, since ageing is associated with an impaired glucagon response and reduced hypoglycemia awareness.”
She calls for more research to address this in both frail and nonfrail older adults and suggests that a “hierarchical approach” to TIR goals may be best in older adults, focusing first on achieving a low time below range and only then seeking to maximize TIR.
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