Hypoglycemia Reduction and Changes in Hemoglobin A1c in the ASPIRE In-Home Study

Background: ASPIRE In-Home randomized 247 subjects with type 1 diabetes to sensor-augmented pump therapy with or without the Threshold Suspend (TS) feature, which interrupts insulin delivery at a preset sensor glucose value. We studied the effects of TS on nocturnal hypoglycemia (NH) in relation to baseline hemoglobin A1c (A1C) and change in A1C during the study. Materials and Methods: NH event rates and mean area under curve (AUC) of NH events were evaluated at different levels of baseline A1C (<7%, 7-8%, and >8%) and at different levels of changes in A1C (less than -0.3% [decreased], -0.3% to 0.3% [stable], and >0.3% [increased]), in the TS Group compared with the Control Group (sensor-augmented pump only). Results: In the TS Group, 27.9% of the NH events were accompanied by a confirmatory blood glucose value, compared with 39.3% in the Control Group. Among subjects with baseline A1C levels of <7% or 7-8%, those in the TS Group had significantly lower NH event rates than those in the Control Group (P=0.001 and P=0.004, respectively). Among subjects with decreased or stable A1C levels, those in the TS Group had significantly lower NH event rates, and the events had lower AUCs (P≤0.001 for each). Among subjects with increased A1C levels, those in the TS Group had NH events with significantly lower AUCs (P<0.001). Conclusions: Use of the TS feature was associated with decreases in the rate and severity (as measured by AUC) of NH events in many subjects, including those with low baseline A1C levels and those whose A1C values decreased during the study period. Use of the TS feature can help protect against hypoglycemia in those wishing to intensify diabetes management to achieve target glucose levels.