Hybrid closed-loop control system fares well in T1D patients at risk of hypoglycaemia
Hybrid closed-loop control (HCLC) cuts the risk and frequency of hypoglycaemia relative to sensor-augmented pump (SAP) therapy in type 1 diabetes (T1D) patients at moderate-to-high risk of hypoglycaemia, according to a recent study.
“We can therefore conclude that automated insulin delivery by a hybrid closed-loop system is safe in the vulnerable subpopulation of people who are at moderate-to-high risk for hypoglycaemia,” said researchers.
The study included 42 T1D patients, of whom 21 received HCLC (mean age, 38.3±3.3 years; 52.4 percent male) while 21 were assigned to SAP (mean age, 38.0±3.3 years; 28.6 percent male). In the HCLC arm, low blood glucose index (LBGI) dropped from 2.5 at baseline to 1.3 by the last week of study. This was greater than that observed in the SAP group in the same time span (from 2.1 to 1.8). [Diabetes Technol Ther 2019;doi:10.1089/dia.2019.0018]
“It is evident that this change was rather fast, occurred during the first week of active HCLC and was sustained during the remaining 3 weeks of active HCLC,” said researchers, further noting that the difference in change between the groups achieved statistical significance (F, 15.5; p<0.001).
Similarly, HCLC elicited a 4-week decrease in the percent of time <70 mg/dL (7.2 percent to 2.0 percent) that was significantly greater than that in the SAP arm (5.8 percent to 4.8 percent; p=0.001).
HCLC also resulted in an improvement in percent time within the target range of 70–180 mg/dL (67.8 percent at baseline to 78.2 percent after 4 weeks). In contrast, this metric showed a downward trend in patients who received SAP (65.6 percent to 59.6 percent), leading to a between-group difference that was statistically significant (p<0.001).
“Similar to the LBGI, these effects were evident during the first week of activating HCLC and were sustained thereafter,” said researchers.
Moreover, the percent of time >180 mg/dL dropped from 25.1 percent at baseline to 19.8 percent after 4 weeks in the HCLC group, but increased in the SAP arm (28.6 percent to 35.6 percent; p=0.009).
“Taken together with the overall reduction in glucose variability, these data suggest that HCLC reduced significantly the overall volatility of glucose control and simultaneously reduced the risk for hypoglycaemia,” researchers pointed out.
In terms of safety, researchers reported no serious adverse events, though there were six cases of moderate hyperglycaemia and five of moderate ketonaemia.
“This study focused on the effects of HCLC in a subpopulation of people with T1D, who are at moderate-to-high risk for hypoglycaemia due to hypoglycaemia unawareness or other factors of their glycaemic control,” said researchers. “This subgroup has been typically excluded from previous HCLC studies because automated insulin delivery was deemed too risky for these vulnerable subjects.”
“On the contrary, it is intuitively clear that this is the subgroup that could benefit most from the use of HCLC, particularly if the HCLC system is designed with the primary objective to safeguard against hypoglycaemia,” they added. The present findings thus emphasize that such an approach is safe and effective in these patients.