Safety and efficacy of the predictive low glucose management system in the prevention of hypoglycaemia: protocol for randomised controlled home trial to evaluate the Suspend before low function

One Year Clinical Experience of the First Commercial Hybrid Closed-Loop System

OBJECTIVE

In September 2016, the U.S. Food and Drug Administration approved the Medtronic 670G "hybrid" closed-loop system. In Auto Mode, this system automatically controls basal insulin delivery based on continuous glucose monitoring data but requires users to enter carbohydrates and blood glucose for boluses. To track real-world experience with this first commercial closed-loop device, we prospectively followed pediatric and adult patients starting the 670G system.

RESEARCH DESIGN AND METHODS

This was a 1-year prospective observational study of patients with type 1 diabetes starting the 670G system between May 2017 and May 2018 in clinic.

RESULTS

Of the total of 84 patients who received 670G and consented, 5 never returned for follow-up, with 79 (aged 9-61 years) providing data at 1 week and 3, 6, 9, and/or 12 months after Auto Mode initiation. For the 86% (68 out of 79) with 1-week data, 99% (67 out of 68) successfully started. By 3 months, at least 28% (22 out of 79) had stopped using Auto Mode; at 6 months, 34% (27 out of 79); at 9 months, 35% (28 out of 79); and by 12 months, 33% (26 out of 79). The primary reason for continuing Auto Mode was desire for increased time in range. Reasons for discontinuation included sensor issues in 62% (16 out of 26), problems obtaining supplies in 12% (3 out of 26), hypoglycemia fear in 12% (3 out of 26), multiple daily injection preference in 8% (2 out of 26), and sports in 8% (2 out of 26). At all visits, there was a significant correlation between hemoglobin A_1c (HbA_1c) and Auto Mode utilization.

CONCLUSIONS

While Auto Mode utilization correlates with improved glycemic control, a focus on usability and human factors is necessary to ensure use of Auto Mode. Alarms and sensor calibration are a major patient concern, which future technology should alleviate.

Realizing a Closed-Loop (Artificial Pancreas) System for the Treatment of Type 1 Diabetes

Recent, rapid changes in the treatment of type 1 diabetes have allowed for commercialization of an "artificial pancreas" that is better described as a closed-loop controller of insulin delivery. This review presents the current state of closed-loop control systems and expected future developments with a discussion of the human factor issues in allowing automation of glucose control. The goal of these systems is to minimize or prevent both short-term and long-term complications from diabetes and to decrease the daily burden of managing diabetes. The closed-loop systems are generally very effective and safe at night, have allowed for improved sleep, and have decreased the burden of diabetes management overnight. However, there are still significant barriers to achieving excellent daytime glucose control while simultaneously decreasing the burden of daytime diabetes management. These systems use a subcutaneous continuous glucose sensor, an algorithm that accounts for the current glucose and rate of change of the glucose, and the amount of insulin that has already been delivered to safely deliver insulin to control hyperglycemia, while minimizing the risk of hypoglycemia. The future challenge will be to allow for full closed-loop control with minimal burden on the patient during the day, alleviating meal announcements, carbohydrate counting, alerts, and maintenance. The human factors involved with interfacing with a closed-loop system and allowing the system to take control of diabetes management are significant. It is important to find a balance between enthusiasm and realistic expectations and experiences with the closed-loop system.

A Review of Predictive Low Glucose Suspend and Its Effectiveness in Preventing Nocturnal Hypoglycemia

To evaluate the effectiveness of predictive low glucose suspend (PLGS) systems within sensor-augmented insulin infusion pumps at preventing nocturnal hypoglycemia in patients with type 1 diabetes (DM1), we performed a systematic review and meta-analysis of randomized crossover trials. Pubmed and Google Scholar were searched for randomized crossover trials, published between January 2013 and July 2018, in nonpregnant outpatients with DM1, which compared event rates during PLGS overnight periods and non-PLGS overnight periods. The primary outcome was the proportion of overnight periods with one or more hypoglycemic measurement. When available, individual patient data were used to assess the effect of clustering measurements within patients. Four studies (272 patients, 10,735 patient-nights: 5422 PLGS and 5313 non-PLGS) were included in the meta-analysis. Two studies reported patient-level data that permitted assessment of the effect of clustering measurements within patients. The effect on the risk difference was minimal. The proportion of overnight periods with one or more episodes of hypoglycemia was 19.6% for the PLGS periods and 27.8% for the non-PLGS periods. Based on the pooled estimate, PLGS overnight periods were associated with an 8.8% lower risk of hypoglycemia (risk difference -0.088; 95% CI -0.119 to -0.056, I² = 67.4%, τ² = 0.0006, 4 studies). PLGS systems can reduce nocturnal hypoglycemic events in patients with DM1.

Combining continuous glucose monitoring and insulin pumps to automatically tune the basal insulin infusion in diabetes therapy: a review

For individuals affected by Type 1 diabetes (T1D), a chronic disease in which the pancreas does not produce any insulin, maintaining the blood glucose (BG) concentration as much as possible within the safety range (70–180 mg/dl) allows avoiding short- and long-term complications. The tuning of exogenous insulin infusion can be difficult, especially because of the inter- and intra-day variability of physiological and behavioral factors. Continuous glucose monitoring (CGM) sensors, which monitor glucose concentration in the subcutaneous tissue almost continuously, allowed improving the detection of critical hypo- and hyper-glycemic episodes. Moreover, their integration with insulin pumps for continuous subcutaneous insulin infusion allowed developing algorithms that automatically tune insulin dosing based on CGM measurements in order to mitigate the incidence of critical episodes. In this work, we aim at reviewing the literature on methods for CGM-based automatic attenuation or suspension of basal insulin with a focus on algorithms, their implementation in commercial devices and clinical evidence of their effectiveness and safety.

Impact of Sensor-Augmented Pump Therapy with Predictive Low-Glucose Suspend Function on Glycemic Control and Patient Satisfaction in Adults and Children with Type 1 Diabetes

AIMS

The aim was to evaluate the effectiveness of sensor-augmented pump therapy with predictive low-glucose suspend function (SAP-PLGS) in real-world use in children and adults with type 1 diabetes (T1D).

METHODS

Patients with T1D treated with the MiniMed 640G^® pump with PLGS function at three referral hospitals were retrospectively evaluated. Hb_A1c at baseline and at 6, 12, 18, and 24 months was analyzed. Two weeks of data from pumps, sensors, and/or glucose meters were downloaded. Patients completed satisfaction questionnaires at the last follow-up visit.

RESULTS

A total of 162 patients were included. Mean age was 32 ± 17 years, 28% were (n = 46) children, and 29% (n = 47) were with a history of severe hypoglycemia. Median follow-up was 12 months (6-18). Hb_A1c was reduced from 55 ± 9 to 54 ± 8 mmol/mol (7.2% ± 0.8% to 7.1% ± 0.7%) at 12 months (P < 0.03, n = 100). In patients with suboptimal control, there was a reduction in Hb_A1c from 66% ± 7% to 61 ± 10 mmol/mol (8.2% ± 0.6% to 7.7% ± 0.9%) at the end of follow-up (n = 26, P < 0.01). Three percent (n = 5) of the patients experienced severe hypoglycemia during follow-up. A reduction in the percentage of self-monitoring of blood glucose values <70 mg/dL was achieved (10% ± 7% to 6% ± 5%, P = 0.001, n = 144). Time in range 70-180 mg/dL was 67% ± 13% at the end of follow-up and predictors of a higher time in range were identified. The use of sensors was high (86%) and 73% of the patients showed high satisfaction. In patients using sensors at baseline (n = 54), the time spent at <54 and <70 mg/dL was reduced.

CONCLUSION

SAP-PLGS reduces hypoglycemia frequency while maintaining glycemic control in adults and children under real-life conditions.

Predictive hyperglycemia and hypoglycemia minimization: In-home double-blind randomized controlled evaluation in children and young adolescents

OBJECTIVE

The primary objective of this trial was to evaluate the feasibility, safety, and efficacy of a predictive hyperglycemia and hypoglycemia minimization (PHHM) system vs predictive low glucose suspension (PLGS) alone in optimizing overnight glucose control in children 6 to 14 years old.

RESEARCH DESIGN AND METHODS

Twenty-eight participants 6 to 14 years old with T1D duration ≥1 year with daily insulin therapy ≥12 months and on insulin pump therapy for ≥6 months were randomized per night into PHHM mode or PLGS-only mode for 42 nights. The primary outcome was percentage of time in sensor-measured range 70 to 180 mg/dL in the overnight period.

RESULTS

The addition of automated insulin delivery with PHHM increased time in target range (70-180 mg/dL) from 66 ± 11% during PLGS nights to 76 ± 9% during PHHM nights (P<.001), without increasing hypoglycemia as measured by time below various thresholds. Average morning blood glucose improved from 176 ± 28 mg/dL following PLGS nights to 154 ± 19 mg/dL following PHHM nights (P<.001).

CONCLUSIONS

The PHHM system was effective in optimizing overnight glycemic control, significantly increasing time in range, lowering mean glucose, and decreasing glycemic variability compared to PLGS alone in children 6 to 14 years old.

Unexpected Management Behaviors in Adolescents With Type 1 Diabetes Using Sensor-Augmented Pump Therapy

BACKGROUND

Continuous glucose monitoring can improve glycemic outcomes in individuals with type 1 diabetes. However, the constant exposure to real-time glucose levels can sometimes lead the individual to make some risky choices to address the glycemic excursions. Hence, the purpose of this study was to explore the aberrant management behaviors of youth with type 1 diabetes on sensor-augmented pump therapy (SAPT).

METHODS

Participants in a clinical trial using SAPT on Medtronic MiniMed™ 640G pump who experienced deteriorating glycemic control or unexplained hypoglycemia were identified by the health care professional. The pump and/or sensor data uploaded to CareLink™ Therapy Management Software were reviewed in these participants.

RESULTS

Uncharacteristic management behaviors were identified in five adolescent males. Continuous exposure to high glucose levels resulted in obsessive behaviors displaying a perfectionistic attitude in two participants. Multiple boluses were delivered frequently as uneaten carbohydrates in participant 1 while participant 2 resorted to delivery of extra insulin by cannula fills. In contrast, participant 3 chose to remain hyperglycemic to avoid weight gain while participant 4 trusted the system and used sensor glucose readings for calibrations, with resultant deterioration in glycemic control in both participants. On the other hand, participant 5, due to mistrust in the pump suspend function, consumed carbohydrates with downward glucose trends with rebound hyperglycemia.

CONCLUSIONS

Constant exposure to real-time data can lead to unsafe management responses in adolescents with the behavior influenced by trust or mistrust in the system. Adolescents should be empowered with problem-solving strategies for safe management.

Reduction in Hypoglycemia With the Predictive Low-Glucose Management System: A Long-term Randomized Controlled Trial in Adolescents With Type 1 Diabetes

OBJECTIVE

Short-term studies with automated systems that suspend basal insulin when hypoglycemia is predicted have shown a reduction in hypoglycemia; however, efficacy and safety have not been established in long-term trials.

RESEARCH DESIGN AND METHODS

We conducted a 6-month, multicenter, randomized controlled trial in children and adolescents with type 1 diabetes using the Medtronic MiniMed 640G pump with Suspend before low (predictive low-glucose management [PLGM]) compared with sensor-augmented pump therapy (SAPT) alone. The primary outcome was percentage time in hypoglycemia with sensor glucose (SG) <3.5 mmol/L (63 mg/dL).

RESULTS

In an intent-to-treat analysis of 154 subjects, 74 subjects were randomized to SAPT and 80 subjects to PLGM. At baseline, the time with SG <3.5 mmol/L was 3.0% and 2.8% in the SAPT and PLGM groups, respectively. During the study, PLGM was associated with a reduction in hypoglycemia compared with SAPT (% time SG <3.5 mmol/L: SAPT vs. PLGM, 2.6 vs. 1.5, P < 0.0001). A similar effect was also noted in time with SG <3 mmol/L (P < 0.0001). This reduction was seen both during day and night (P < 0.0001). Hypoglycemic events (SG <3.5 mmol/L for >20 min) also declined with PLGM (SAPT vs. PLGM: events/patient-year 227 vs. 139, P < 0.001). There was no difference in glycated hemoglobin (HbA_1c) at 6 months (SAPT 7.6 ± 1.0% vs. PLGM 7.8 ± 0.8%, P = 0.35). No change in quality of life measures was reported by participants/parents in either group. There were no PLGM-related serious adverse events.

CONCLUSIONS

In children and adolescents with type 1 diabetes, PLGM reduced hypoglycemia without deterioration in glycemic control.

"Let the Algorithm Do the Work": Reduction of Hypoglycemia Using Sensor-Augmented Pump Therapy with Predictive Insulin Suspension (SmartGuard) in Pediatric Type 1 Diabetes Patients

BACKGROUND

A sensor-augmented insulin pump (SAP) using the MiniMed^® 640G system with SmartGuard™ technology allows an automatic stop of insulin delivery based on prediction of low glucose levels. Since pediatric patients are particularly prone to hypoglycemia, this device may offer additional protection beyond conventional sensor-augmented therapy.

METHODS

This prospective, pediatric multicenter user evaluation assessed 6 weeks of SAP with SmartGuard (threshold setting for hypoglycemia: 70 mg/dL) compared to a preceding period of 2 weeks with SAP only. The primary outcome was the potential reduction in the frequency of hypoglycemic episodes and hypoglycemic intensity (area under the curve [AUC] and time <70 mg/dL).

RESULTS

The study included 24 patients with at least 3 months of insulin pump use (average age: 11.6 ± 5.1 years, 15 female, average type 1 diabetes duration: 7.5 ± 4.2 years, mean ± SD) who had on average 3.2 ± 1.0 predictive suspensions/patient/day. The mean sensor glucose minimum during suspension was 78 ± 6 mg/dL and the average suspension time was 155 ± 47 min/day. Use of SmartGuard in patients treated as per the protocol (n = 18) reduced the number of instances in which the glucose level was <70 mg/dL (1.02 ± 0.52 to 0.72 ± 0.36; P = 0.027), as well as AUC <70 mg/dL (0.76 ± 0.73 to 0.38 ± 0.24; P = 0.027) and the time/day the level fell below 70 mg/dL (73 ± 56 to 31 ± 22 min). The reduction of hypoglycemia was not associated with a significant change in mean glucose concentration (171 ± 26 to 180 ± 19 mg/dL, P = 0.111) and HbA1c (7.5% ± 0.5% to 7.6% ± 0.7%, (P = 0.329). Manual resumption of insulin delivery followed by carbohydrate intake resulted in significantly higher glucose levels 1 h after suspension compared to SmartGuard suspensions with automatic resume (190.8 ± 26.5 vs. 138.7 ± 10.3 mg/dL; P < 0.001).

CONCLUSIONS

SmartGuard technology significantly reduced the risk for hypoglycemia in pediatric type 1 diabetes patients without increasing HbA1c. Patients must be educated that when using combining predictive low-glucose insulin suspension technology, extra carbohydrate intake in response to an alarm combined with manual resumption is likely to cause rebound hyperglycemia. The best results were achieved when the user did not interfere with pump operation.

Prevention of Insulin-Induced Hypoglycemia in Type 1 Diabetes with Predictive Low Glucose Management System

BACKGROUND

Sensor-augmented pump therapy (SAPT) with algorithms to predict impending low blood glucose and suspend insulin delivery has the potential to reduce hypoglycemia exposure. The aim of this study was to determine whether predictive low glucose management (PLGM) system is effective in preventing insulin-induced hypoglycemia in controlled experiments.

METHODS

Two protocols were used to induce hypoglycemia in an in-clinic environment. (A) Insulin bolus: Insulin was administered as a manual bolus through the pump. (B) Increased basal insulin: Hypoglycemia was induced by increasing basal rates overnight to 180%. For both protocols, participants were randomized and studied on 2 separate days; a control day with SAPT alone and an intervention day with SAPT and PLGM activated. The predictive algorithm was programmed to suspend basal insulin infusion when sensor glucose was predicted to be <80 mg/dL in 30 min. The primary outcome was the requirement for hypoglycemia treatment (symptomatic hypoglycemia or plasma glucose <50 mg/dL) and was compared in both control and intervention arms.

RESULTS

With insulin bolus, 24/28 participants required hypoglycemia treatment with SAPT alone compared to 5/28 participants when PLGM was activated (P ≤ 0.001). With increased basal rates, all the eight SAPT-alone participants required treatment for hypoglycemia compared to only one with SAPT and PLGM. There was no post pump-suspend hyperglycemia with insulin bolus (P = 0.4) or increased basal rates (P = 0.69) in participants with 2-h pump suspension on intervention days.

CONCLUSIONS

SAPT with PLGM reduced the requirement for hypoglycemia treatment following insulin-induced hypoglycemia in an in-clinic setting.