Older age ‘not a barrier’ to closed-loop insulin delivery for type 1 diabetes
medwireNews: Findings from the ORACL trial suggest that closed-loop insulin delivery results in better glycemic control than sensor-augmented pump therapy among older adults with longstanding type 1 diabetes.
The open-label crossover study involved 30 participants aged at least 60 years (average 67 years) without frailty who had a median diabetes duration of 38 years. These people received 4 months of closed-loop insulin delivery with the Medtronic MiniMed 670G system and 4 months of sensor-augmented pump therapy in a random order.
Sybil McAuley (The University of Melbourne, Victoria, Australia) and ORACL co-investigators report that the average time spent in the target glucose range of 3.9–10.0 mmol/L (70.3–180.2 mg/dL) as measured by continuous glucose monitoring (CGM) was significantly higher during closed-loop versus sensor-augmented pump delivery, at 75.2% versus 69.0%.
This time in range (TIR) increase of 6.2 percentage points with closed-loop delivery equated to an extra 90 minutes per day, “a difference considered clinically significant,” say the researchers.
They add that “[a]ll prespecified CGM metrics favored closed-loop over the sensor-augmented pump,” with the greatest benefits seen at night.
In the overnight period, participants spent a significantly lower average proportion of time in hypoglycemia during closed-loop versus sensor-augmented pump treatment, with rates of 0.38% versus 1.33% for the 3.9 mmol/L hypoglycemia threshold, 0.08% versus 0.35% for the 3.3 mmol/L (59.5 mg/dL) threshold, and 0.03% versus 0.13% for the 3.0 mmol/L (54.1 mg/dL) threshold.
McAuley and colleagues calculated that at the individual level, closed-loop insulin delivery resulted in an extra 10 people (33% of the study population) achieving all four international consensus recommendations for CGM targets in older adults:
- More than 50% TIR;
- Less than 50% of time with glucose levels above 10.0 mmol/L;
- Less than 10% of time with glucose levels above 19 mmol/L (250.5 mg/dL); and
- Less than 1% of time with glucose levels below 3.9 mmol/L.
There was no significant difference in median glycated hemoglobin levels during the closed-loop compared with the sensor-augmented pump period, at 7.3% and 7.5% (56.0 and 58.0 mmol/mol), respectively. The team notes that this finding “is perhaps not surprising,” given that the average baseline glycated hemoglobin level of 7.6% (60 mmol/mol) “did not have much room for improvement.”
The investigators say that “[n]o major safety issues were identified in the trial.” There were no serious adverse events (SAEs) during closed-loop delivery, and two SAEs – one episode of diabetic ketoacidosis and one of vitreous hemorrhage (unrelated to the trial) – during sensor-augmented pump treatment.
“In conclusion, older age is not a barrier to closed-loop therapy,” write McAuley et al in Diabetes Care.
They recommend that future studies should “examine the effects and safety of closed loop among people with frailty or major cognitive impairment and among individuals with less favorable preexisting glycemia.”
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