Hybrid Closed Loop in Adults With Type 1 Diabetes and Severely Impaired Hypoglycemia Awareness.

BACKGROUND: Benefits of hybrid closed-loop (HCL) systems in a high-risk group with type 1 diabetes and impaired awareness of hypoglycemia (IAH) have not been well-explored. METHODS: Adults with Edmonton HYPO scores ≥1047 were randomized to 26-weeks HCL (MiniMed™ 670G) vs standard therapy (multiple daily injections or insulin pump) without continuous glucose monitoring (CGM) (control). Primary outcome was percentage CGM time-in-range (TIR; 70-180 mg/dL) at 23 to 26 weeks post-randomization. Major secondary endpoints included magnitude of change in counter-regulatory hormones and autonomic symptom responses to hypoglycemia at 26-weeks post-randomization. A post hoc analysis evaluated glycemia risk index (GRI) comparing HCL with control groups at 26 weeks post-randomization. RESULTS: Nine participants (median [interquartile range (IQR)] age 51 [41, 59] years; 44% male; enrolment HYPO score 1183 [1058, 1308]; Clarke score 6 [6, 6]; n = 5 [HCL]; n = 4 [control]) completed the study. Time-in-range was higher using HCL vs control (70% [68, 74%] vs 48% [44, 50%], P = .014). Time <70 mg/dL did not differ (HCL 3.8% [2.7, 3.9] vs control 6.5% [4.3, 8.6], P = .14) although hypoglycemia episode duration was shorter (30 vs 50 minutes, P < .001) with HCL. Glycemia risk index was lower with HCL vs control (38.1 [30.0, 39.2] vs 70.8 [58.5, 72.4], P = .014). Following 6 months of HCL use, greater dopamine (24.0 [12.3, 27.6] vs -18.5 [-36.5, -4.8], P = .014), and growth hormone (6.3 [4.6, 16.8] vs 0.5 [-0.8, 3.0], P = .050) responses to hypoglycemia were observed. CONCLUSIONS: Six months of HCL use in high-risk adults with severe IAH increased glucose TIR and improved GRI without increased hypoglycemia, and partially restored counter-regulatory responses. CLINICAL TRIAL REGISTRATION: ACTRN12617000520336.

Driving-Related Glucose Patterns Among Older Adults with Type 1 Diabetes.

Older adults with type 1 diabetes may face challenges driving safely. Glucose "above-5-to-drive" is often recommended for insulin-treated diabetes to minimize hypoglycemia while driving. However, the effectiveness of this recommendation among older adults has not been evaluated. Older drivers with type 1 diabetes were assessed while using sensor-augmented insulin pumps during a 2-week clinical trial run-in. Twenty-three drivers (median age 69 years [interquartile range; IQR 65-72]; diabetes duration 37 years [20-45]) undertook 618 trips (duration 10 min [5-21]). Most trips (n = 535; 87%) were <30 min duration; 9 trips (1.5%) exceeded 90 min and 3 trips (0.5%) exceeded 120 min. Pre-trip continuous glucose monitoring (CGM) was >5.0 mmol/L for 577 trips (93%) and none of these had CGM <3.9 mmol/L during driving (including 8 trips >90 min and 3 trips >120 min). During 41 trips with pre-trip CGM ≤5.0 mmol/L, 11 trips had CGM <3.9 mmol/L. Seventy-one CGM alerts occurred during 60 trips (10%), of which 54 of 71 alerts (76%) were unrelated to hypoglycemia. Our findings support a glucose "above-5-to-drive" recommendation to avoid CGM-detected hypoglycemia among older drivers, including for prolonged drives, and highlight the importance of active CGM low-glucose alerts to prevent hypoglycemia during driving. Driving-related CGM usability and alert functionality warrant investigation. Clinical trial ACTRN1261900515190.

Interactive calculator to estimate insulin sensitivity in type 1 diabetes.

The gold standard for measuring insulin sensitivity (IS) is the hyperinsulinemic-euglycemic clamp, a time, costly, and labor-intensive research tool. A low insulin sensitivity is associated with a complication-risk in type 1 diabetes. Various formulae using clinical data have been developed and correlated with measured IS in type 1 diabetes. We consolidated multiple formulae into an online calculator (bit.ly/estimated-GDR), enabling comparison of IS and its probability of IS <4.45 mg/kg/min (low) or >6.50 mg/kg/min (high), as measured in a validation set of clamps in 104 adults with type 1 diabetes. Insulin sensitivity calculations using different formulae varied significantly, with correlations (R2) ranging 0.005-0.87 with agreement in detecting low and high glucose disposal rates in the range 49-93% and 89-100%, respectively. We demonstrate that although the calculated IS varies between formulae, their interpretation remains consistent. Our free online calculator offers a user-friendly tool for individual IS calculations and also offers efficient batch processing of data for research.

Real-world lived experience of older adults with type 1 diabetes after an automated insulin delivery trial.

AIMS: First-generation closed-loop automated insulin delivery improves glycaemia and psychosocial outcomes among older adults with type 1 diabetes in clinical trials. However, no study has previously assessed real-world lived experience of older adults using closed-loop therapy outside a trial environment. METHODS: Semi-structured interviews were conducted with older adults who were pre-existing insulin pump users and previously completed the OldeR Adult Closed-Loop (ORACL) randomised trial. Interviews focused on perceptions of diabetes technology use, and factors influencing decisions regarding continuation. RESULTS: Twenty-eight participants, mean age 70 years (SD 5), were interviewed at median 650 days (IQR 608-694) after their final ORACL trial visit. At interview, 23 participants (82%) were still using a commercial closed-loop system (requiring manual input for prandial insulin bolus doses). Themes discussed in interviews relating to closed-loop system use included sustained psychosocial benefits, cost and retirement considerations and usability frustrations relating to sensor accuracy and system alarms. Of the five participants who had discontinued, reasons included cost, continuous glucose monitoring-associated difficulties and usability frustrations. Cost was the largest consideration regarding continued use; most participants considered the increased ease of diabetes management to be worth the associated costs, though cost was prohibitive for some. CONCLUSIONS: Almost 2 years after completing a closed-loop clinical trial, closed-loop automated insulin delivery remains the preferred type 1 diabetes therapy for the majority of older adult participants. Chronological age is not a barrier to real-world successful use of diabetes technology. Identifying age-related barriers, and solutions, to diabetes technology use among older adults is warranted.

Stimulation parameters for directional vagus nerve stimulation.

BACKGROUND: Autonomic nerve stimulation is used as a treatment for a growing number of diseases. We have previously demonstrated that application of efferent vagus nerve stimulation (eVNS) has promising glucose lowering effects in a rat model of type 2 diabetes. This paradigm combines high frequency pulsatile stimulation to block nerve activation in the afferent direction with low frequency stimulation to activate the efferent nerve section. In this study we explored the effects of the parameters for nerve blocking on the ability to inhibit nerve activation in the afferent direction. The overarching aim is to establish a blocking stimulation strategy that could be applied using commercially available implantable pulse generators used in the clinic. METHODS: Male rats (n = 20) had the anterior abdominal vagus nerve implanted with a multi-electrode cuff. Evoked compound action potentials (ECAP) were recorded at the proximal end of the electrode cuff. The efficacy of high frequency stimulation to block the afferent ECAP was assessed by changes in the threshold and saturation level of the response. Blocking frequency and duty cycle of the blocking pulses were varied while maintaining a constant 4 mA current amplitude. RESULTS: During application of blocking at lower frequencies (≤ 4 kHz), the ECAP threshold increased (ANOVA, p < 0.001) and saturation level decreased (p < 0.001). Application of higher duty cycles (> 70%) led to an increase in evoked neural response threshold (p < 0.001) and a decrease in saturation level (p < 0.001). During the application of a constant pulse width and frequency (1 or 1.6 kHz, > 70% duty cycle), the charge delivered per pulse had a significant influence on the magnitude of the block (ANOVA, p = 0.003), and was focal (< 2 mm range). CONCLUSIONS: This study has determined the range of frequencies, duty cycles and currents of high frequency stimulation that generate an efficacious, focal axonal block of a predominantly C-fiber tract. These findings could have potential application for the treatment of type 2 diabetes.

Continuous Glucose Monitoring-Based Composite Metrics: A Review and Assessment of Performance in Recent-Onset and Long-Duration Type 1 Diabetes.

This study examined correlations between continuous glucose monitoring (CGM)-based composite metrics and standard glucose metrics within CGM data sets from individuals with recent-onset and long-duration type 1 diabetes. First, a literature review and critique of published CGM-based composite metrics was undertaken. Second, composite metric results were calculated for the two CGM data sets and correlations with six standard glucose metrics were examined. Fourteen composite metrics met selection criteria; these metrics focused on overall glycemia (n = 8), glycemic variability (n = 4), and hypoglycemia (n = 2), respectively. Results for the two diabetes cohorts were similar. All eight metrics focusing on overall glycemia strongly correlated with glucose time in range; none strongly correlated with time below range. The eight overall glycemia-focused and two hypoglycemia-focused composite metrics were all sensitive to automated insulin delivery therapeutic intervention. Until a composite metric can adequately capture both achieved target glycemia and hypoglycemia burden, the current two-dimensional CGM assessment approach may offer greatest clinical utility.

Independent euglycaemic hyperinsulinaemic clamp studies validate clinically applicable formulae to estimate insulin sensitivity in people with type 1 diabetes.

BACKGROUND AND AIM: Low insulin sensitivity (IS) increases Type 1 diabetes (T1D) complication risk and can be estimated by simple formulae developed from complex euglycemic hyperinsulinaemic clamp studies. We aimed to validate these formulae using independent clamp data. METHODS: Clamps were performed in 104 T1D adults. Measured glucose disposal rate (GDR) was correlated with eGDR and eLog10 M/I calculated by five IS formulae. RESULTS: Correlations ranged between 0.23-0.40. Two IS formulae (by the authors), using age, sex, HDL-C, HbA1c, pulse pressure, BMI, and waist-hip-ratio had the highest correlation with measured GDR and the best performance in detecting low IS.

Lived experience of older adults with type 1 diabetes using closed-loop automated insulin delivery in a randomised trial.

AIM: To explore the lived experience of older adults with type 1 diabetes using closed-loop automated insulin delivery, an area previously receiving minimal attention. METHODS: Semi-structured interviews were conducted with adults aged 60 years or older with long-duration type 1 diabetes who participated in a randomised, open-label, two-stage crossover trial comparing first-generation closed-loop therapy (MiniMed 670G) versus sensor-augmented pump therapy. Interview recordings were transcribed, thematically analysed and assessed. RESULTS: Twenty-one older adults participated in interviews after using closed-loop therapy. Twenty were functionally independent, without frailty or major cognitive impairment; one was dependent on caregiver assistance, including for diabetes management. Quality of life benefits were identified, including improved sleep and reduced diabetes-related psychological burden, in the context of experiencing improved glucose levels. Gaps between expectations and reality of closed-loop therapy were also experienced, encountering disappointment amongst some participants. The cost was perceived as a barrier to continued closed-loop access post-trial. Usability issues were identified, such as disruptive overnight alarms and sensor inaccuracy. CONCLUSIONS: The lived experience of older adults without frailty or major cognitive impairment using first-generation closed-loop therapy was mainly positive and concordant with glycaemic benefits found in the trial. Older adults' lived experience using automated insulin delivery beyond trial environments requires exploration; moreover, the usability needs of older adults should be considered during future device development.

Glucose profiles of older adults with type 1 diabetes using sensor-augmented pump therapy in Australia: pre-randomisation results from the ORACL study.

BACKGROUND: Older adults with type 1 diabetes are recommended modified glucose targets. However, data on the effects of diabetes technology in older age are scarce. We assessed older adults established on sensor-augmented insulin pump therapy during clinical trial run-in and compared their continuous glucose monitoring (CGM) profiles with consensus recommendations. We aimed to provide insight into the applicability of currently recommended CGM-based targets while accounting for current Diabetes UK guidelines. METHODS: In this analysis, adults aged 60 years or older with type 1 diabetes with a duration of at least 10 years and entering the Older Adult Closed Loop (ORACL) trial were studied. The trial was done at two tertiary hospitals in Australia. Individuals who were independent with diabetes self-management, as well as those receiving caregiver assistance for their diabetes management, were eligible for inclusion. Participants underwent baseline clinical assessment, which included medical history and examination, testing for frailty, functional ability, cognitive functioning, psychosocial wellbeing, and subjective sleep quality; fasting venous blood samples were collected for C-peptide, glucose, and glycated haemoglobin A1c measurement. Sensor-augmented pumps, carbohydrate-counting education, and diabetes education were provided to participants by diabetes nurse educators, dietitians, and endocrinologists experienced in type 1 diabetes clinical care. CGM data were subsequently collected for 2 weeks during sensor-augmented pump therapy. The ORACL trial is registered with the Australian New Zealand Clinical Trial Registry, ACTRN12619000515190. FINDINGS: Our analysis included all 30 participants who completed the ORACL trial run-in-19 (63%) women and 11 (37%) men (mean age 67 years [SD 5], median diabetes duration 38 years [IQR 20-47], and insulin total daily dose 0·55 units [0·41-0·66] per kg bodyweight). Ten (33%) of 30 participants had impaired hypoglycaemia awareness and six (20%) were pre-frail; none were frail. The median CGM time in range 3·9-10·0 mmol/L was 71% (IQR 64-79). The time spent with glucose above 10·0 mmol/L was 27% (18-35) and above 13·9 mmol/L was 3·9% (2·4-10·2). The time with glucose below 3·9 mmol/L was 2·0% (1·2-3·1) and the time below 3·0 mmol/L was 0·2% (0·1-0·4). Only two (7%) of 30 participants met all CGM-based consensus recommendations modified for older adults. Time in hypoglycaemia was lower among the 16 participants with predictive low-glucose alerts enabled than among the 14 participants not using predictive low-glucose alerts (median difference -1·1 percentage points [95% CI -2·0 to -0·1]; p=0·038). This difference was even greater overnight (-2·3 percentage points [-3·2 to -1·0]; p=0·0018). One serious adverse event occurred (elective cardiac stent). INTERPRETATION: Using sensor-augmented pumps after multidisciplinary education, this group of older adults without frailty achieved a time in range far exceeding minimum consensus recommendations. However, the current stringent hypoglycaemia recommendations for all older adults were not met. Predictive low alerts could reduce hypoglycaemia, particularly overnight. Investigation into the effectiveness of CGM-based targets that consider frailty, functional status, and diabetes therapies for older adults is warranted. FUNDING: JDRF and Diabetes Australia.

Late Afternoon Vigorous Exercise Increases Postmeal but Not Overnight Hypoglycemia in Adults with Type 1 Diabetes Managed with Automated Insulin Delivery.

Aim: To compare evening and overnight hypoglycemia risk after late afternoon exercise with a nonexercise control day in adults with type 1 diabetes using automated insulin delivery (AID). Methods: Thirty adults with type 1 diabetes using AID (Minimed 670G) performed in random order 40 min high intensity interval aerobic exercise (HIE), resistance (RE), and moderate intensity aerobic exercise (MIE) exercise each separated by >1 week. The closed-loop set-point was temporarily increased 2 h pre-exercise and a snack eaten if plasma glucose was ≤126 mg/dL pre-exercise. Exercise commenced at ∼16:00. A standardized meal was eaten at ∼20:40. Hypoglycemic events were defined as a continuous glucose monitor (CGM) reading <70 mg/dL for ≥15 min. Four-hour postevening meal and overnight (00:00-06:00) CGM metrics for exercise were compared with the prior nonexercise day. Results: There was no severe hypoglycemia. Between 00:00 and 06:00, the proportion of nights with hypoglycemia did not differ postexercise versus control for HIE (18% vs. 11%; P = 0.688), RE (4% vs. 14%; P = 0.375), and MIE (7% vs. 14%; P = 0.625). Time in range (TIR) (70-180 mg/dL), >75% for all nights, did not differ between exercise conditions and control. Hypoglycemia episodes postmeal after exercise versus control did not differ for HIE (22% vs. 7%; P = 0.219) and MIE (10% vs. 14%; P > 0.999), but were greater post-RE (39% vs. 10%; P = 0.012). Conclusions: Overnight TIR was excellent with AID without increased hypoglycemia postexercise between 00:00 and 06:00 compared with nonexercise days. In contrast, hypoglycemia risk was increased after the first meal post-RE, suggesting the importance of greater vigilance and specific guidelines for meal-time dosing, particularly with vigorous RE. ACTRN12618000905268.

Insulin antibodies are prevalent in adults with type 1 diabetes referred for islet cell transplantation and are modified by islet transplantation and immunosuppression: an Australian experience.

We have analysed insulin antibodies in 149 adults with type 1 diabetes and 2859 people without diabetes. We have determined that insulin antibody levels are higher in adults with, versus without, diabetes and that the levels are falling, and more patients are becoming antibody-negative post islet cell transplantation.

Closed-Loop Insulin Delivery Effects on Glycemia During Sleep and Sleep Quality in Older Adults with Type 1 Diabetes: Results from the ORACL Trial.

Sleep-related effects of closed-loop therapy among older adults with type 1 diabetes have not been well established. In the OldeR Adult Closed-Loop (ORACL) randomized, crossover trial of first-generation closed-loop therapy (MiniMed 670G), participants wore actigraphy and completed sleep diaries for 14-day periods at stage end. During objectively measured sleep (actigraphy) with closed-loop versus sensor-augmented pump therapy, glucose time-in-range 70-180 mg/dL (3.9-10.0 mmol/L) was greater (90.3% vs. 78.7%, respectively; difference 8.2 percentage points [95% confidence interval {CI} 1.5 to 13.0]; P = 0.008), and there were fewer sensor hypoglycemia episodes (18 vs. 43, respectively; incident rate ratio 0.40 [95% CI 0.20 to 0.55]; P = 0.007). Sleep quality recorded daily was worse with closed-loop therapy (P = 0.006); Pittsburgh Sleep Quality Index did not differ. There were 30% more system alarms during monitored sleep with closed-loop therapy (P < 0.001). First-generation closed-loop therapy has important glycemic benefits during sleep for older adults, with deterioration in some sleep quality measures. Sleep quality warrants prioritization and investigation during advancement of closed-loop technology.

Driving with Type 1 Diabetes: Real-World Evidence to Support Starting Glucose Level and Frequency of Monitoring During Journeys.

There is limited evidence supporting the recommendation that drivers with insulin-treated diabetes need to start journeys with glucose >90 mg/dL. Glucose levels of drivers with type 1 diabetes were monitored for 3 weeks using masked continuous glucose monitoring (CGM). Eighteen drivers (median [IQR] age 40 [35, 51] years; 11 men) undertook 475 trips (duration 15 [13, 21] min). Hypoglycemia did not occur in any trip starting with glucose >90 mg/dL (92%; n = 436). Thirteen drivers recorded at least one trip (total n = 39) starting with glucose <90 mg/dL. Among these, driving glucose was <70 mg/dL in five drivers (38%) during 10 trips (26%). Among five drivers (28%), a ≥ 36 mg/dL drop was observed within 20 min of starting their journey. Journey duration was positively associated with maximum glucose change. These findings support current guidelines to start driving with glucose >90 mg/dL, and to be aware that glucose levels may change significantly within 20 min. A CGM-based, in-vehicle display could provide glucose information and alerts that are compatible with safe driving. Clinical Trial Registration number: ACTRN12617000520336.

Closed-Loop Insulin Delivery Versus Sensor-Augmented Pump Therapy in Older Adults With Type 1 Diabetes (ORACL): A Randomized, Crossover Trial.

OBJECTIVE: To assess the efficacy and safety of closed-loop insulin delivery compared with sensor-augmented pump therapy among older adults with type 1 diabetes. RESEARCH DESIGN AND METHODS: This open-label, randomized (1:1), crossover trial compared 4 months of closed-loop versus sensor-augmented pump therapy. Eligible adults were aged ≥60 years, with type 1 diabetes (duration ≥10 years), using an insulin pump. The primary outcome was continuous glucose monitoring (CGM) time in range (TIR; 3.9-10.0 mmol/L). RESULTS: There were 30 participants (mean age 67 [SD 5] years), with median type 1 diabetes duration of 38 years (interquartile range [IQR] 20-47), randomized (n = 15 to each sequence); all completed the trial. The mean TIR was 75.2% (SD 6.3) during the closed-loop stage and 69.0% (9.1) during the sensor-augmented pump stage (difference of 6.2 percentage points [95% CI 4.4 to 8.0]; P < 0.0001). All prespecified CGM metrics favored closed loop over the sensor-augmented pump; benefits were greatest overnight. Closed loop reduced CGM time <3.9 mmol/L during 24 h/day by 0.5 percentage points (95% CI 0.3 to 1.1; P = 0.0005) and overnight by 0.8 percentage points (0.4 to 1.1; P < 0.0001) compared with sensor-augmented pump. There was no significant difference in HbA1c between closed-loop versus sensor-augmented pump stages (7.3% [IQR, 7.1-7.5] (56 mmol/mol [54-59]) vs. 7.5% [7.1-7.9] (59 mmol/mol [54-62]), respectively; P = 0.13). Three severe hypoglycemia events occurred during the closed-loop stage and two occurred during the sensor-augmented pump stage; no hypoglycemic events required hospitalization. One episode of diabetic ketoacidosis occurred during the sensor-augmented pump stage; no serious adverse events occurred during the closed-loop stage. CONCLUSIONS: Closed-loop therapy is an effective treatment option for older adults with long-duration type 1 diabetes, and no safety issues were identified. These older adults had higher TIR accompanied by less time below range during closed loop than during sensor-augmented pump therapy. Of particular clinical importance, closed loop reduced the time spent in hypoglycemic range overnight.

A Randomized Crossover Trial Comparing Glucose Control During Moderate-Intensity, High-Intensity, and Resistance Exercise With Hybrid Closed-Loop Insulin Delivery While Profiling Potential Additional Signals in Adults With Type 1 Diabetes.

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: This study was an 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 MiniMed 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.

Adapting Protocols or Models for Use in Insulin-Requiring Diabetes and Islet Transplant Recipients.

The authors' perspective is described regarding modifications made in their clinic to glucose challenge protocols and mathematical models in order to estimate insulin secretion, insulin sensitivity and glucose effectiveness in patients living with Insulin-Requiring Diabetes and patients who received Pancreatic Islet Transplants to treat Type I diabetes (T1D) with Impaired Awareness of Hypoglycemia. The evolutions are described of protocols and models for use in T1D, and Insulin-Requiring Type 2 Diabetes (T2D) that were the basis for studies in the Islet Recipients. In each group, the need for modifications, and how the protocols and models were adapted is discussed. How the ongoing application of the adaptations is clarifying the Islet pathophysiology in the Islet Transplant Recipients is outlined.

Fast-Acting Insulin Aspart Versus Insulin Aspart Using a Second-Generation Hybrid Closed-Loop System in Adults With Type 1 Diabetes: A Randomized, Open-Label, Crossover Trial.

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%.