Post-breakfast closed-loop glucose control is improved when accompanied with carbohydrate-matching bolus compared to weight-dependent bolus.

AIM: We compared post-breakfast closed-loop glucose control either matched with a carbohydrate-matching bolus or a weight-dependent bolus. METHODS: Twelve adults with type 1 diabetes consumed a 75 g CHO breakfast on two occasions. In random order, the breakfast was accompanied by a full carbohydrate-matching insulin bolus (8.30 U [7.50 U-11.50 U]) or a partial weight-dependent insulin bolus (0.047 U/kg; 3.45 U [2.95 U-3.75 U]). Postprandial glucose was regulated by sensor-responsive insulin and glucagon delivery. RESULTS: Glucose control after the weight-dependent bolus was safe and feasible (glucose values returned to pre-prandial levels after 5 h). However, 5-hr incremental area under the curve and percentage of time above 10 mmol/L were lower after the full bolus compared to the partial bolus (IAUC, 2.1 [0.8-4.2] mmol/L/hr vs 8.3 [6.5-11.4] mmol/L/hr; time in hyperglycaemia, 24% [6%-29%] vs 50% [25%-63%]; P < 0.001). CONCLUSIONS: Post-breakfast closed-loop glucose control without carbohydrate counting, but based on weight-dependent bolus is feasible but a carbohydrate-matching bolus provides better glucose control. CLINICAL TRIAL REGISTRY: NCT01519102.