Hybrid Closed-Loop Control Is Safe and Effective for People with Type 1 Diabetes Who Are at Moderate to High Risk for Hypoglycemia

Background: Typically, closed-loop control (CLC) studies excluded patients with significant hypoglycemia. We evaluated the effectiveness of hybrid CLC (HCLC) versus sensor-augmented pump (SAP) in reducing hypoglycemia in this high-risk population. Methods: Forty-four subjects with type 1 diabetes, 25 women, 37 +/- 2 years old, HbA1c 7.4% +/- 0.2% (57 +/- 1.5 mmol/mol), diabetes duration 19 +/- 2 years, on insulin pump, were enrolled at the University of Virginia (N = 33) and Stanford University (N = 11). Eligibility: increased risk of hypoglycemia confirmed by 1 week of blinded continuous glucose monitor (CGM); randomized to 4 weeks of home use of either HCLC or SAP. Primary/secondary outcomes: risk for hypoglycemia measured by the low blood glucose index (LBGI)/CGM-based time in ranges. Results: Values reported: mean +/- standard deviation. From baseline to the final week of study: LBGI decreased more on HCLC (2.51 +/- 1.17 to 1.28 +/- 0.5) than on SAP (2.1 +/- 1.05 to 1.79 +/- 0.98), P < 0.001; percent time below 70 mg/dL (3.9 mmol/L) decreased on HCLC (7.2% +/- 5.3% to 2.0% +/- 1.4%) but not on SAP (5.8% +/- 4.7% to 4.8% +/- 4.5%), P = 0.001; percent time within the target range 70-180 mg/dL (3.9-10 mmol/L) increased on HCLC (67.8% +/- 13.5% to 78.2% +/- 10%) but decreased on SAP (65.6% +/- 12.9% to 59.6% +/- 16.5%), P < 0.001; percent time above 180 mg/dL (10 mmol/L) decreased on HCLC (25.1% +/- 15.3% to 19.8% +/- 10.1%) but increased on SAP (28.6% +/- 14.6% to 35.6% +/- 17.6%), P = 0.009. Mean glucose did not change significantly on HCLC (144.9 +/- 27.9 to 143.8 +/- 14.4 mg/dL [8.1 +/- 1.6 to 8.0 +/- 0.8 mmol/L]) or SAP (152.5 +/- 24.3 to 162.4 +/- 28.2 [8.5 +/- 1.4 to 9.0 +/- 1.6]), P = ns. Conclusions: Compared with SAP therapy, HCLC reduced the risk and frequency of hypoglycemia, while improving time in target range and reducing hyperglycemia in people at moderate to high risk of hypoglycemia.