Feasibility of Long-Term Closed-Loop Control: A Multicenter 6-Month Trial of 24/7 Automated Insulin Delivery.

BACKGROUND: In the past few years, the artificial pancreas-the commonly accepted term for closed-loop control (CLC) of blood glucose in diabetes-has become a hot topic in research and technology development. In the summer of 2014, we initiated a 6-month trial evaluating the safety of 24/7 CLC during free-living conditions. RESEARCH DESIGN AND METHODS: Following an initial 1-month Phase 1, 14 individuals (10 males/4 females) with type 1 diabetes at three clinical centers in the United States and one in Italy continued with a 5-month Phase 2, which included 24/7 CLC using the wireless portable Diabetes Assistant (DiAs) developed at the University of Virginia Center for Diabetes Technology. Median subject characteristics were age 45 years, duration of diabetes 27 years, total daily insulin 0.53 U/kg/day, and baseline HbA1c 7.2% (55 mmol/mol). RESULTS: Compared with the baseline observation period, the frequency of hypoglycemia below 3.9 mmol/L during the last 3 months of CLC was lower: 4.1% versus 1.3%, P < 0.001. This was accompanied by a downward trend in HbA1c from 7.2% (55 mmol/mol) to 7.0% (53 mmol/mol) at 6 months. HbA1c improvement was correlated with system use (Spearman r = 0.55). The user experience was favorable with identified benefit particularly at night and overall trust in the system. There were no serious adverse events, severe hypoglycemia, or diabetic ketoacidosis. CONCLUSION: We conclude that CLC technology has matured and is safe for prolonged use in patients' natural environment. Based on these promising results, a large randomized trial is warranted to assess long-term CLC efficacy and safety.

Multinational Home Use of Closed-Loop Control Is Safe and Effective.

OBJECTIVE: To evaluate the efficacy of a portable, wearable, wireless artificial pancreas system (the Diabetes Assistant [DiAs] running the Unified Safety System) on glucose control at home in overnight-only and 24/7 closed-loop control (CLC) modes in patients with type 1 diabetes. RESEARCH DESIGN AND METHODS: At six clinical centers in four countries, 30 participants 18-66 years old with type 1 diabetes (43% female, 96% non-Hispanic white, median type 1 diabetes duration 19 years, median A1C 7.3%) completed the study. The protocol included a 2-week baseline sensor-augmented pump (SAP) period followed by 2 weeks of overnight-only CLC and 2 weeks of 24/7 CLC at home. Glucose control during CLC was compared with the baseline SAP. RESULTS: Glycemic control parameters for overnight-only CLC were improved during the nighttime period compared with baseline for hypoglycemia (time <70 mg/dL, primary end point median 1.1% vs. 3.0%; P < 0.001), time in target (70-180 mg/dL: 75% vs. 61%; P < 0.001), and glucose variability (coefficient of variation: 30% vs. 36%; P < 0.001). Similar improvements for day/night combined were observed with 24/7 CLC compared with baseline: 1.7% vs. 4.1%, P < 0.001; 73% vs. 65%, P < 0.001; and 34% vs. 38%, P < 0.001, respectively. CONCLUSIONS: CLC running on a smartphone (DiAs) in the home environment was safe and effective. Overnight-only CLC reduced hypoglycemia and increased time in range overnight and increased time in range during the day; 24/7 CLC reduced hypoglycemia and increased time in range both overnight and during the day. Compared with overnight-only CLC, 24/7 CLC provided additional hypoglycemia protection during the day.

Day and Night Closed-Loop Control Using the Integrated Medtronic Hybrid Closed-Loop System in Type 1 Diabetes at Diabetes Camp.

OBJECTIVE: To evaluate the feasibility and efficacy of a fully integrated hybrid closed-loop (HCL) system (Medtronic MiniMed Inc., Northridge, CA), in day and night closed-loop control in subjects with type 1 diabetes, both in an inpatient setting and during 6 days at diabetes camp. RESEARCH DESIGN AND METHODS: The Medtronic MiniMed HCL system consists of a fourth generation (4S) glucose sensor, a sensor transmitter, and an insulin pump using a modified proportional-integral-derivative (PID) insulin feedback algorithm with safety constraints. Eight subjects were studied over 48 h in an inpatient setting. This was followed by a study of 21 subjects for 6 days at diabetes camp, randomized to either the closed-loop control group using the HCL system or to the group using the Medtronic MiniMed 530G with threshold suspend (control group). RESULTS: The overall mean sensor glucose percent time in range 70-180 mg/dL was similar between the groups (73.1% vs. 69.9%, control vs. HCL, respectively) (P = 0.580). Meter glucose values between 70 and 180 mg/dL were also similar between the groups (73.6% vs. 63.2%, control vs. HCL, respectively) (P = 0.086). The mean absolute relative difference of the 4S sensor was 10.8 ± 10.2%, when compared with plasma glucose values in the inpatient setting, and 12.6 ± 11.0% compared with capillary Bayer CONTOUR NEXT LINK glucose meter values during 6 days at camp. CONCLUSIONS: In the first clinical study of this fully integrated system using an investigational PID algorithm, the system did not demonstrate improved glucose control compared with sensor-augmented pump therapy alone. The system demonstrated good connectivity and improved sensor performance.

Accuracy evaluation of blood glucose monitoring systems in children on overnight closed-loop control.

This pilot study evaluated the difference in accuracy between the Bayer Contour® Next (CN) and HemoCue® (HC) glucose monitoring systems in children with type 1 diabetes participating in overnight closed-loop studies. Subjects aged 10-18 years old were admitted to a clinical research center and glucose values were obtained every 30 minutes overnight. Glucose values were measured using whole blood samples for CN and HC readings and results were compared to Yellow Springs Instrument (YSI) reference values obtained with plasma from the same sample. System accuracy was compared using mean absolute relative difference (MARD) and International Organization for Standardization (ISO) accuracy standards. A total of 28 subjects were enrolled in the study. Glucose measurements were evaluated at 457 time points. CN performed better than HC with an average MARD of 3.13% compared to 10.73% for HC (P < .001). With a limited sample size, CN met ISO criteria (2003 and 2013) at all glucose ranges while HC did not. CN performed very well, and would make an excellent meter for future closed-loop studies outside of a research center.

Randomized trial of infusion set function: steel versus teflon.

BACKGROUND: This study compared infusion set function for up to 1 week using either a Teflon(®) (Dupont(™), Wilmington, DE) catheter or a steel catheter for insulin pump therapy in type 1 diabetes mellitus. SUBJECTS AND METHODS: Twenty subjects participating in a randomized, open-labeled, crossover study were asked to wear two Quick-Set(®) and two Sure-T(®) infusion sets (both from Medtronic Minimed, Northridge, CA) until the infusion set failed or was worn for 1 week. All subjects wore a MiniMed continuous glucose monitoring system for the duration of the study. RESULTS: One subject withdrew from the study. There were 38 weeks of Sure-T wear and 39 weeks of Quick-Set wear with no difference in the survival curves of the infusion sets. There was, however, a 15% initial failure rate with the Teflon infusion set. After 7 days, both types of infusion sets had a 64% failure rate. Overall, 30% failed because of hyperglycemia and a failed correction dose, 13% were removed for pain, 10% were pulled out by accident, 10% had erythema and/or induration of>10 mm, 5% fell out because of loss of adhesion, and 4% were removed for infection. The main predictor of length of wear was the individual subject. There was no increase in hyperglycemia or daily insulin requirements when an infusion set was successfully used for 7 days (n=25 of 77 weeks). CONCLUSIONS: We found no difference between steel and Teflon infusion sets in their function over 7 days, although 15% of Teflon sets failed because of kinking on insertion. The strongest predictor of prolonged 7-day infusion set function was the individual subject, not the type of infusion set.

Severe hypoglycemia and diabetic ketoacidosis among youth with type 1 diabetes in the T1D Exchange clinic registry.

OBJECTIVE: Severe hypoglycemia (SH) and diabetic ketoacidosis (DKA) are common serious acute complications of type 1 diabetes (T1D). The aim of this study was to determine the frequency of SH and DKA and identify factors related to their occurrence in the T1D Exchange pediatric and young adult cohort. RESEARCH DESIGN AND METHODS: The analysis included 13 487 participants in the T1D Exchange clinic registry aged 2 to <26 yr with T1D ≥2 yr. Separate logistic regression models were used to evaluate the association of baseline demographic and clinical factors with the occurrence of SH or DKA in the prior 12 months. RESULTS: Non-White race, no private health insurance, and lower household income were associated with higher frequencies of both SH and DKA (p < 0.001). SH frequency was highest in children <6 yr old (p = 0.005), but across the age range, SH was not associated with hemoglobin A1c (HbA1c) levels after controlling for other factors (p = 0.72). DKA frequency was highest in adolescents (p < 0.001) and associated with higher HbA1c (p < 0.001). CONCLUSIONS: Our data show that poor glycemic control increases the risk of DKA but does not protect against SH in youth and young adults with type 1 diabetes. The high frequencies of SH and DKA observed in disadvantaged minorities with T1D highlight the need for targeted interventions and new treatment paradigms for patients in these high risk groups.

Diabetic ketoacidosis at diabetes onset: still an all too common threat in youth.

OBJECTIVE: To define the demographic and clinical characteristics of children at the onset of type 1 diabetes (T1D), with particular attention to the frequency of diabetic ketoacidosis (DKA). STUDY DESIGN: The Pediatric Diabetes Consortium enrolled children with new-onset T1D into a common database. For this report, eligible subjects were aged <19 years, had a pH or HCO(3) value recorded at diagnosis, and were positive for at least one diabetes-associated autoantibody. Of the 1054 children enrolled, 805 met the inclusion criteria. A pH of <7.3 and/or HCO(3) value of <15 mEq/L defined DKA. Data collected included height, weight, hemoglobin A1c, and demographic information (eg, race/ethnicity, health insurance status, parental education, family income). RESULTS: The 805 children had a mean age of 9.2 years, 50% were female; 63% were non-Hispanic Caucasian. Overall, 34% of the children presented in DKA, half with moderate or severe DKA (pH <7.2). The risk for DKA was estimated as 54% in children aged <3 years and 33% in those aged ≥ 3 years (P = .006). In multivariate analysis, younger age (P = .002), lack of private health insurance (P < .001), African-American race (P = .01), and no family history of T1D (P = .001) were independently predictive of DKA. The mean initial hemoglobin A1c was higher in the children with DKA compared with those without DKA (12.5% ± 1.9% vs 11.1% ± 2.4%; P < .001). CONCLUSION: The incidence of DKA in children at the onset of T1D remains high, with approximately one-third presenting with DKA and one-sixth with moderate or severe DKA. Increased awareness of T1D in the medical and lay communities is needed to decrease the incidence of this life-threatening complication.