Predictive insulin-suspend algorithm cuts hypoglycemia without consequent hyperglycemia
medwireNews: The Tandem Basal-IQ predictive low-glucose suspend (PLGS) insulin delivery system significantly reduces the proportion of time adults and children spend in hypoglycemia during 24-hour usage, show findings from the randomized crossover PROLOG trial.
During 3 weeks of using the system, study participants spent an average of 3.1% of their time in hypoglycemia (blood glucose <70 mg/dL), compared with 4.5% during the 3 weeks they used a sensor-augmented insulin pump. This represented a significant 31% reduction.
The 102 patients with type 1 diabetes who completed both phases of the trial did so in a randomly assigned order, after a run-in period to get used to the technology. They were aged between 6 and 72 years, with 58% being younger than 18 years of age.
John Lum (Jaeb Center for Health Research, Tampa, Florida, USA) and co-researchers say the results “support the findings of our previous overnight-only studies.” However, they note that when patients did experience hypoglycemia with the PLGS system, the duration of the episode was no shorter than with sensor-augmented pump delivery.
They suggest that this could relate to the amount of insulin already in a patient’s body at the time of pump suspension. “Patients and providers should be aware that prolonged hypoglycemic events, though uncommon, can still occur with PLGS,” the team writes in Diabetes Care.
The reduced time in hypoglycemia did not come at the expense of increased hyperglycemia; indeed, the overall time spent within the blood glucose range of 70–180 mg/dL increased by a significant 2%, from 63% with the sensor-augmented pump to 65% with the PLGS system, equivalent to an additional 30 minutes per day spent in range.
The researchers say these findings are contrary to results with some other PLGS systems and suggest this may be because the Tandem Basal-IQ algorithm resumes insulin delivery at “the first glucose reading past the nadir” rather than at a specific threshold. This resulted in insulin being suspended for 18 minutes on average, compared with nearly an hour in other studies, they say.
Insulin delivery was suspended for a cumulative average of 104 minutes per day (72 min in the daytime; 32 min at night), resulting in around a 4% reduction in basal insulin use without affecting bolus insulin dose.
“This appears to suggest that the algorithm was successful in decreasing basal insulin delivery only during times when basal insulin was unwanted without affecting insulin delivery during other periods of the day,” say Lum and team.
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