OBJECTIVE To compare glucose control with hybrid closed-loop (HCL) when challenged by high intensity exercise (HIE), moderate intensity exercise (MIE), and resistance exercise (RE) while profiling counterregulatory hormones, lactate, ketones, and kinetic data in adults with type 1 diabetes. RESEARCH DESIGN AND METHODS Open-label multisite randomized crossover trial. Adults with type 1 diabetes undertook 40 min of HIE, MIE, and RE in random order while using HCL (Medtronic MiniMedTM 670G) with a temporary target set 2 h prior to and during exercise and 15 g carbohydrates if pre-exercise glucose was <126 mg/dL to prevent hypoglycemia. Primary outcome was median (interquartile range) continuous glucose monitoring time-in-range (TIR; 70–180 mg/dL) for 14 h post–exercise commencement. Accelerometer data and venous glucose, ketones, lactate, and counterregulatory hormones were measured for 280 min post–exercise commencement. RESULTS Median TIR was 81% (67, 93%), 91% (80, 94%), and 80% (73, 89%) for 0–14 h post–exercise commencement for HIE, MIE, and RE, respectively (n = 30), with no difference between exercise types (MIE vs. HIE; P = 0.11, MIE vs. RE, P = 0.11; and HIE vs. RE, P = 0.90). Time-below-range was 0% for all exercise bouts. For HIE and RE compared with MIE, there were greater increases, respectively, in noradrenaline (P = 0.01 and P = 0.004), cortisol (P < 0.001 and P = 0.001), lactate (P ≤ 0.001 and P ≤ 0.001), and heart rate (P = 0.007 and P = 0.015). During HIE compared with MIE, there were greater increases in growth hormone (P = 0.024). CONCLUSIONS Under controlled conditions, HCL provided satisfactory glucose control with no difference between exercise type. Lactate, counterregulatory hormones, and kinetic data differentiate type and intensity of exercise, and their measurement may help inform insulin needs during exercise. However, their potential utility as modulators of insulin dosing will be limited by the pharmacokinetics of subcutaneous insulin delivery.

OBJECTIVE To evaluate glucose control using fast-acting insulin aspart (faster aspart) compared with insulin aspart (IAsp) delivered by the MiniMed Advanced Hybrid Closed-Loop (AHCL) system in adults with type 1 diabetes. RESEARCH DESIGN AND METHODS In this randomized, open-label, crossover study, participants were assigned to receive faster aspart or IAsp in random order. Stages 1 and 2 comprised of 6 weeks in closed loop, preceded by 2 weeks in open loop. This was followed by stage 3, whereby participants changed directly back to the insulin formulation used in stage 1 for 1 week in closed loop. Participants chose their own meals except for two standardized meal tests, a missed meal bolus and late meal bolus. The primary outcome was the percentage of time sensor glucose values were from 70 to 180 mg/dL (time in range [TIR]). RESULTS Twenty-five adults (52% male) were recruited; the median (interquartile range) age was 48 (37, 57) years, and the median HbA1c was 7.0% (6.6, 7.2) (53 [49, 55] mmol/mol). Faster aspart demonstrated greater overall TIR compared with IAsp (82.3% [78.5, 83.7] vs. 79.6% [77.0, 83.4], respectively; mean difference 1.9% [0.5, 3.3]; P = 0.007). Four-hour postprandial glucose TIR was higher using faster aspart compared with IAsp for all meals combined (73.6% [69.4, 80.2] vs. 72.1% [64.5, 78.5], respectively; median difference 3.5% [1.0, 7.3]; P = 0.003). There was no ketoacidosis or severe hypoglycemia. CONCLUSIONS Faster aspart safely improved glucose control compared with IAsp in a group of adults with well-controlled type 1 diabetes using AHCL. The modest improvement was mainly related to mealtime glycemia. While the primary outcome demonstrated statistical significance, the clinical impact may be small, given an overall difference in TIR of 1.9%.

The JDRF Australia Adult Hybrid Closed Loop (HCL) Study Group recently published results of the first randomized trial (ACTRN12617000520336, HREC-D088/16) of the commercially available HCL MiniMed™ 670G system (Medtronic, Northridge, CA). 1,2 The trial compared six-months HCL vs. standard therapy [self-monitoring of blood glucose (SMBG) with multiple-daily-injections or continuous subcutaneous insulin infusion (CSII) without continuous glucose monitoring (CGM)] in adults with type 1 diabetes. It demonstrated that HCL improves glucose management, including time-inrange (70-180 mg/dl), all other CGM metrics, HbA1c and 1,5 anhydroglucitol. 1 As there is limited evidence regarding HCL use with exercise 3 we conducted a sub-study comparing glucose management in 10 adults with type 1 diabetes undertaking 45 min of moderate-intensity exercise (MIE) and high-intensity interval exercise (HIIE) in random order separated by 7-days, with 6 subjects (computer) randomized to HCL and 4 to standard therapy. After 5 min warm-up (25% VO2max) MIE comprised 40 min of continuous exercise at 70% of their anerobic threshold. HIIE comprised 6 repetitions of 4 min at intensity half-way between anerobic threshold and maximal capacity, separated by 2 to 4 min rest. HCL participants implemented an increased glucose target of 150 mg/dL (from 120 mg/dL) 1 h pre-exercise until 15 min post-exercise.