Closed-loop system in the management of diabetes: past, present, and future

Differential signaling effects of blood glucose on delay discounting in individuals with and without type 1 diabetes

Based on the signaling hypothesis of blood glucose (BG), a rise in BG levels signals a positive energy budget for healthy individuals but cellular starvation for individuals with type 1 diabetes. We examined this novel prediction and its intervention implications in the context of delay discounting, the degree to which delayed rewards are discounted, and the regulatory effects of insulin ingestion. We recruited 44 adults with type 1 diabetes (mean age 30.8 years, diabetes duration 15.4 years) and recorded their BG levels. The delay discounting rate was measured using the intertemporal choice task, where participants were required to choose between sets of smaller-and-sooner (SS) and larger-and-later (LL) rewards. In addition, 82 age-matched healthy participants were recruited to provide a baseline comparison on delay discounting. Random forest analysis showed that among many diagnostic factors, delay discounting was most dominating in differentiating the individuals with type 1 diabetes from the control participants. A hierarchical linear mixed model revealed that participants with type 1 diabetes had a stronger preference for SS rewards (p < .001) after controlling for covariates. Participants who had insulin delivered before the last meal exhibited a stronger preference for LL rewards compared to after-meal delivery. In contrast, subjective measures (e.g., self-reported hunger) failed to predict the participants' actual BG levels and delay discounting rates. In sum, individuals with type 1 diabetes tend to discount future rewards excessively compared to the control participants. Pre-meal insulin ingestion was associated with a higher LL preference for future rewards.

What is holding back glucometer use? -A comparative study of rural and urban India

BACKGROUND

Self-monitoring of blood glucose (SMBG) is associated with better glycemic control. There have been significant technological advances in blood glucose monitoring in the recent past, but the wider acceptance of these technologies is still debatable.

AIM

This study investigates the adoption of glucometers and the extent of the use of features in rural and urban India.

METHODS

The study uses Bass Model to predict the diffusion of innovation (DOI). Mathematical modeling was used to determine the stage of adoption (using 5-stage of DOI) and the Chi-Square test was used for examining the relationship between depth of implementation (extent of use) and place of residence.

RESULTS

The result of the study suggests that glucometer diffusion of innovation has passed the initial hurdle (chasm) in the urban population and is in the late majority. However, for rural respondents, the adoption of glucometers has just passed the chasm and falls under the early majority stage. The diffusion of innovation of combined rural and urban populations has just entered the late majority zone in 2022. The study suggests that a significant number of people with diabetes are still not using a glucometer and discusses the socio-economic issue related to this phenomenon. The utilization of the potential of a glucometer in SMBG falls under the localized shallow implementation category (not using advanced features).

CONCLUSIONS

The study suggests that the adoption of glucometer has just passed the initial hurdle in rural India, where two-thirds of the Indian population lives. Furthermore, the adoption of advanced glucometers is low among users.

Recent advancement in noninvasive glucose monitoring and closed-loop management system for diabetes

Diabetes can cause many complications, which has become one of the most common diseases that may lead to death. Currently, the number of diabetics continues increasing year by year. Thus,...

Wearable patch delivery system for artificial pancreas health diagnostic-therapeutic application: A review

The advanced stimuli-responsive approaches for on-demand drug delivery systems have received tremendous attention as they have great potential to be integrated with sensing and multi-functional electronics on a flexible and stretchable single platform (all-in-one concept) in order to develop skin-integration with close-loop sensation for personalized diagnostic and therapeutic application. The wearable patch pumps have evolved from reservoir-based to matrix patch and drug-in-adhesive (single-layer or multi-layer) type. In this review, we presented the basic requirements of an artificial pancreas, surveyed the design and technologies used in commercial patch pumps available on the market and provided general information about the latest wearable patch pump. We summarized the various advanced delivery strategies with their mechanisms that have been developed to date and representative examples. Mechanical, electrical, light, thermal, acoustic and glucose-responsive approaches on patch form have been successfully utilized in the controllable transdermal drug delivery manner. We highlighted key challenges associated with wearable transdermal delivery systems, their research direction and future development trends.

Standardized Hybrid Closed-Loop System Reporting

The hybrid closed-loop (HCL) system has been shown to improve glycemic control and reduce hypoglycemia. Optimization of HCL settings requires interpretation of the glucose, insulin, and factors affecting glucose such as food intake and exercise. To the best of our knowledge, there is no published guidance on the standardized reporting of HCL systems. Standardization of HCL reporting would make interpretation of data easy across different systems. We reviewed the literature on patient and provider perspectives on downloading and reporting glucose metric preferences. We also incorporated international consensus on standardized reporting for glucose metrics. We describe a single-page HCL data reporting, referred to here as "artificial pancreas (AP) Dashboard." We propose seven components in the AP Dashboard that can provide detailed information and visualization of glucose, insulin, and HCL-specific metrics. The seven components include (A) glucose metrics, (B) hypoglycemia, (C) insulin, (D) user experience, (E) hyperglycemia, (F) glucose modal-day profile, and (G) insight. A single-page report similar to an electrocardiogram can help providers and patients interpret HCL data easily and take the necessary steps to improve glycemic outcomes. We also describe the optimal sampling duration for HCL data download and color coding for visualization ease. We believe that this is a first step in creating a standardized HCL reporting, which may result in better uptake of the systems. For increased adoption, standardized reporting will require input from providers, patients, diabetes device manufacturers, and regulators.

Design of dual hormone blood glucose therapy and comparison with single hormone using MPC algorithm

The complete automated control and delivery of insulin and glucagon in type 1 diabetes is the developing technology for artificial pancreas. This improves the quality of life of a diabetic patient with the precise infusion. The amount of infusion of these hormones is controlled using a control algorithm, which has the prediction property. The control algorithm model predictive control (MPC) predicts one step ahead and infuses the hormones continuously according to the necessity for the regulation of blood glucose. In this research, the authors propose a MPC control algorithm, which is novel for a dual hormone infusion, for a mathematical model such as Sorenson model, and compare it with the insulin alone or single hormone infusion developed with MPC. Since they aim for complete automatic control and regulation, unmeasured disturbances at a random time are integrated and the performance evaluation is projected through statistical analysis. The blood glucose risk index (BGRI) and control variability grid analysis (CVGA) plot gives the additional evaluation for the comparative results of the two controllers claiming 88% performance by dual hormone evaluated through CVGA plot and 2.05 mg/dl average tracking error, 2.20 BGRI. The MPC developed for dual hormone significantly performs better and the time spent in normal glycaemia is longer while eliminating the risk of hyperglycaemia and hypoglycaemia.

10-Day structured initiation protocol from multiple daily injection to hybrid closed-loop system in children and adolescents with type 1 diabetes

AIM

The aim of this study was to evaluate the 10-day initiation protocol for MiniMed 670G hybrid closed-loop (HCL) system in individuals with type 1 diabetes on multiple daily injection (MDI) in achieving desirable glycemic control.

METHODS

An open-label single-arm, single-center, clinical investigation in children aged 7-18 years on MDI following a structured protocol: 2 days, HCL system assessment; 5 days, HCL system training (2-h sessions on 5 consecutive days with groups of 3-5 participants and families); 3 days, Manual Mode use of HCL system; 84 days, Auto Mode use of the HCL system, cumulating in 10 days from MDI to Auto Mode activation.

RESULTS

A total of 30 children (age 10.24 ± 2.6 years) were enrolled in the study, and all completed the planned 84 days on Auto Mode. The participants used the sensor for a median of 92% of the time and spent a median of 89% in Auto Mode. The mean HbA1c decreased from 8.2 ± 1.4% (66 ± 15.3 mmol/mol) at baseline to 6.7 ± 0.5% (50 ± 5.5 mmol/mol) at the end of the study (p = 0.017). Time in range (70-180 mg/dL) increased from 46.9 ± 18.5% at baseline to 75.6 ± 6.9% in Auto Mode (p < 0.001). This was achieved while spending 2.8% of the time below 70 mg/dL and without any severe hypoglycemia or DKA.

CONCLUSION

Children and adolescents with type 1 diabetes on MDI therapy can successfully initiate the HCL system, using a concise structured 10-day protocol.

Severe Hypoglycemia: Is It Still a Threat for Children and Adolescents With Type 1 Diabetes?

Severe hypoglycemia is defined as a condition with serious cognitive dysfunction, such as a convulsion and coma, requiring external help from other persons. This condition is still lethal and is reported to be the cause of death in 4-10% in children and adolescents with type 1 diabetes. The incidence of severe hypoglycemia in the pediatric population was previously reported as high as more than 50-100 patient-years; however, there was a decline in the frequency of severe hypoglycemia during the past decades, and relationship with glycemic control became weaker than previously reported. A lot of studies have shown the neurological sequelae with severe hypoglycemia as cognitive dysfunction and abnormalities in brain structure. This serious condition also provides negative psychosocial outcomes and undesirable compensatory behaviors. Various possible factors, such as younger age, recurrent hypoglycemia, nocturnal hypoglycemia, and impaired awareness of hypoglycemia, are possible risk factors for developing severe hypoglycemia. A low HbA_1c level is not a predictable value for severe hypoglycemia. Prevention of severe hypoglycemia remains one of the most critical issues in the management of pediatric patients with type 1 diabetes. Advanced technologies, such as continuous glucose monitoring (CGM), intermittently scanned CGM, and sensor-augmented pump therapy with low-glucose suspend system, potentially minimize the occurrence of severe hypoglycemia without worsening overall glycemic control. Hybrid closed-loop system must be the most promising tool for achieving optimal glycemic control with preventing the occurrence of severe hypoglycemia in pediatric patients with type 1 diabetes.

Severe hypoglycemia is associated with high risk for falls in adults with type 1 diabetes

We evaluated fall frequency and factors affecting falls among middle-aged and older adults with type 1 diabetes (T1D) from T1D Exchange Registry. Twenty-nine percent of T1D participants reported falls within the past 12 months. Severe hypoglycemia, diabetic peripheral neuropathy, and depression were associated with falls in adults with T1D.

PURPOSE

Fall is an important risk factor for osteoporotic fracture; we evaluated fall frequency and factors affecting falls among middle-aged and older adults with type 1 diabetes (T1D).

METHODS

Participants aged ≥ 55 years with T1D completed an email-based questionnaire on falls in the prior 12 months. Demographic, clinical, and fall-related information were gathered from the questionnaire; HbA1c was recorded from medical record data extraction.

RESULTS

Four hundred and thirty five adults with T1D completed the fall questionnaire (mean age 64 ± 7 years, 57% females, and 97% were non-Hispanic whites). The mean diabetes duration was 36 years with mean HbA1c of 7.3%. Among the 435 participants, 126 reported at least one fall in the prior 12 months (29%). The fall frequency values in adults (55-64 years) with T1D and older adults (> 65 years) were 26 and 32%, respectively (p = 0.16). There was no significant difference in frequency of fall between female and male participants (31 vs. 26%, p = 0.33). Of 126 participants who had a fall, 44% had injuries due to fall, 24% required medical attention, and 13 participants reported fracture (10%). Severe hypoglycemia (odds ratio (OR) 3.6), diabetic peripheral neuropathy (OR 2.2), and depression (OR 1.7) were associated with falls in adults with T1D. Forty-one percent of participants were fearful of falls.

CONCLUSIONS

This is the first study on prevalence and risk factors for falls suggesting that falls are common in T1D and severe hypoglycemia is a unique diabetes-related factor associated with threefold higher risk for falls.

Optimizing Hybrid Closed-Loop Therapy in Adolescents and Emerging Adults Using the MiniMed 670G System

OBJECTIVE

The MiniMed 670G System is the first commercial hybrid closed-loop (HCL) system for management of type 1 diabetes. Using data from adolescent and young adult participants, we compared insulin delivery patterns and time-in-range metrics in HCL (Auto Mode) and open loop (OL). System alerts, usage profiles, and operational parameters were examined to provide suggestions for optimal clinical use of the system.

RESEARCH DESIGN AND METHODS

Data from 31 adolescent and young adult participants (14-26 years old) at three clinical sites in the 670G pivotal trial were analyzed. Participants had a 2-week run-in period in OL, followed by a 3-month in-home study phase with HCL functionality enabled. Data were compared between baseline OL and HCL use after 1 week, 1 month, 2 months, and 3 months.

RESULTS

Carbohydrate-to-insulin (C-to-I) ratios were more aggressive for all meals with HCL compared with baseline OL. Total daily insulin dose and basal-to-bolus ratio did not change during the trial. Time in range increased 14% with use of Auto Mode after 3 months (P < 0.001), and HbA_1c decreased 0.75%. Auto Mode exits were primarily due to sensor/insulin delivery alerts and hyperglycemia. The percentage of time in Auto Mode gradually declined from 87%, with a final use rate of 72% (-15%).

CONCLUSIONS

In transitioning young patients to the 670G system, providers should anticipate immediate C-to-I ratio adjustments while also assessing active insulin time. Users should anticipate occasional Auto Mode exits, which can be reduced by following system instructions and reliably bolusing for meals. Unique 670G system functionality requires ongoing clinical guidance and education from providers.

Role of Mobile Technology to Improve Diabetes Care in Adults with Type 1 Diabetes: The Remote-T1D Study iBGStar® in Type 1 Diabetes Management

INTRODUCTION

The role of mobile technology in patient-reported outcomes (PRO) and glycemic control in adults with type 1 diabetes (T1D) needs further evaluation.

METHODS

The single-center, prospective, 6-month, open-label, investigator-initiated study randomized 100 subjects with T1D in a 1:1 fashion to a control group using self-monitoring of blood glucose (SMBG) with Accu-Chek Nano® and an intervention group using SMBG with iPhone plus glucose meter (iBGStar®). The primary endpoint was the change in PRO (hypoglycemia fear score, behavior and worry subscores). Secondary outcomes were the improvement in glycemic variability indices and the reduction in A1c values.

RESULTS

Baseline demographics and glycosylated hemoglobin (A1c) values were similar in the two groups. There was a significant decrease in A1c value at 6 months in iBGStar® group compared to the control group (-0.16 vs. -0.51, p = 0.04). The total insulin dose increased significantly in the iBGStar® group at 3 months but did not change at 6 months. The hypoglycemia fear scale (PRO) improved in both groups at 6 months (-1.4 ± 10.0 vs. -3.9 ± 12.5, p = 0.32).

CONCLUSION

The use of iBGStar® resulted in better glycemic control and improvement in some PRO (hypoglycemia fear and behavior scores) compared to the control group at 6 months with no increased risk of hypoglycemia.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov: NCT01825382.

FUNDING

Sanofi.

A robust fixed point transformation-based approach for type 1 diabetes control

Modeling and control of diabetes mellitus (DM) are difficult due to the highly nonlinear attitude, time-delay effects, the impulse kind input signals and the lack of continuously available blood glucose (BG) level to be regulated. Regarding the mentioned problems, identification of DM model is crucial. Furthermore, due to the lack of information about the internal states (which cannot be measured in everyday life) and because the BG level is not available in every moment over time, adaptive robust control design method regardless exact model dependency would successfully handle these unfavorable effects without simplifications. The recently developed nonlinear robust fixed point transformation (RFPT)-based controller design method requires only a roughly approximate model in order to realize the controller structure. Moreover, parallel simulated approximate models-in order to provide additional internal information-can be used with the method. In this paper, the usability of the novel RFPT-based technique is demonstrated on the physiological problem of diabetes.

Proportional Insulin Infusion in Closed-Loop Control of Blood Glucose

A differential equation model is formulated that describes the dynamics of glucose concentration in blood circulation. The model accounts for the intake of food, expenditure of calories and the control of glucose levels by insulin and glucagon. These and other hormones affect the blood glucose level in various ways. In this study only main effects are taken into consideration. Moreover, by making a quasi-steady state approximation the model is reduced to a single nonlinear differential equation of which parameters are fit to data from healthy subjects. Feedback provided by insulin plays a key role in the control of the blood glucose level. Reduced β-cell function and insulin resistance may hamper this process. With the present model it is shown how by closed-loop control these defects, in an organic way, can be compensated with continuous infusion of exogenous insulin.

Psychosocial Impact of the Bionic Pancreas During Summer Camp

BACKGROUND

The psychosocial impact of the bionic pancreas (BP) was assessed among children attending diabetes camp.

METHODS

Nineteen children were randomly assigned for 5 days to the BP condition and 5 days to the control condition in a crossover design.

RESULTS

Significant reductions in hypoglycemic fear and regimen burden were found. Children felt less burdened or worried about diabetes and felt freer to do things they enjoyed while using the BP. Children wished the BP responded to out of range numbers faster and expressed annoyance about carrying around the necessary equipment.

CONCLUSIONS

Children may experience improved psychosocial outcomes following use of BP while expressing key areas of user concern. Future studies in less controlled environments with larger sample sizes can determine if these findings are generalizable to other groups.

Insulin delivery methods: Past, present and future

Many patients with advanced type 2 diabetes mellitus (T2DM) and all patients with T1DM require insulin to keep blood glucose levels in the target range. The most common route of insulin administration is subcutaneous insulin injections. There are many ways to deliver insulin subcutaneously such as vials and syringes, insulin pens, and insulin pumps. Though subcutaneous insulin delivery is the standard route of insulin administration, it is associated with injection pain, needle phobia, lipodystrophy, noncompliance and peripheral hyperinsulinemia. Therefore, the need exists for delivering insulin in a minimally invasive or noninvasive and in most physiological way. Inhaled insulin was the first approved noninvasive and alternative way to deliver insulin, but it has been withdrawn from the market. Technologies are being explored to make the noninvasive delivery of insulin possible. Some of the routes of insulin administration that are under investigation are oral, buccal, nasal, peritoneal and transdermal. This review article focuses on the past, present and future of various insulin delivery techniques. This article has focused on different possible routes of insulin administration with its advantages and limitation and possible scope for the new drug development.

Pursuit of a perfect insulin

Insulin remains indispensable in the treatment of diabetes, but its use is hampered by its narrow therapeutic index. Although advances in peptide chemistry and recombinant DNA-based macromolecule synthesis have enabled the synthesis of structurally optimized insulin analogues, the growing epidemics of obesity and diabetes have emphasized the need for diabetes therapies that are more efficacious, safe and convenient. Accordingly, a broad set of drug candidates, targeting hyperglycaemia plus other disease abnormalities, is now progressing through the clinic. The development of an insulin therapy that is responsive to glucose concentration remains an ultimate goal, with initial prototypes now reaching the proof-of-concept stage. Simultaneously, the first alternatives to injectable delivery have progressed to registration.

The Hypoglycaemia-Hyperglycaemia Minimizer System in the Management of Type 1 Diabetes

Living with type 1 diabetes (T1D) presents many challenges in terms of daily living. Insulin users need to frequently monitor their blood glucose levels and take multiple injections per day and/or multiple boluses through an insulin infusion pump, with the consequences of failing to match the insulin dose to the body's needs resulting in hypoglycaemia and hyperglycaemia. The former can result in seizures, coma and even death; the latter can have both acute and long-term health implications. Many patients with T1D also fail to meet their treatment goals. In order to reduce the burdens of self-administering insulin, and improve efficacy and safety, there is a need to at least partially remove the patient from the loop via a closed-loop 'artificial pancreas’ system. The Hypoglycaemia-Hyperglycaemia Minimizer (HHM) System, comprising a continuous, subcutaneous insulin infusion pump, continuous glucose monitor (CGM) and closed-loop insulin dosing algorithm, is able to predict changes in blood glucose and adjust insulin delivery accordingly to help keep the patient at normal glucose levels. Early clinical data indicate that this system is feasible, effective and safe, and has the potential to dramatically improve the therapeutic outcomes and quality of life for people with T1D.

Successful Application of Closed-Loop Artificial Pancreas Therapy After Islet Autotransplantation

Total pancreatectomy with islet autotransplantation (TPIAT) may relieve the pain of chronic pancreatitis while avoiding postsurgical diabetes. Minimizing hyperglycemia after TPIAT limits beta cell apoptosis during islet engraftment. Closed-loop (CL) therapy combining an insulin pump with a continuous glucose monitor (CGM) has not been investigated previously in islet transplant recipients. Our objective was to determine the feasibility and efficacy of CL therapy to maintain glucose profiles close to normoglycemia following TPIAT. Fourteen adult subjects (36% male; aged 35.9 ± 11.4 years) were randomized to subcutaneous insulin via CL pump (n = 7) or multiple daily injections with blinded CGM (n = 7) for 72 h at transition from intravenous to subcutaneous insulin. Mean serum glucose values were significantly lower in the CL pump group than in the control group (111 ± 4 vs. 130 ± 13 mg/dL; p = 0.003) without increased risk of hypoglycemia (percentage of time <70 mg/dL: CL pump 1.9%, control 4.8%; p = 0.46). Results from this pilot study suggest that CL therapy is superior to conventional therapy in maintaining euglycemia without increased hypoglycemia. This technology shows significant promise to safely maintain euglycemic targets during the period of islet engraftment following islet transplantation.

An Overview of Insulin Pumps and Glucose Sensors for the Generalist

Continuous subcutaneous insulin, or the insulin pump, has gained popularity and sophistication as a near-physiologic programmable method of insulin delivery that is flexible and lifestyle-friendly. The introduction of continuous monitoring with glucose sensors provides unprecedented access to, and prediction of, a patient’s blood glucose levels. Efforts are underway to integrate the two technologies, from “sensor-augmented” and “sensor-driven” pumps to a fully-automated and independent sensing-and-delivery system. Implantable pumps and an early-phase “bionic pancreas” are also in active development. Fine-tuned “pancreas replacement” promises to be one of the many avenues that offers hope for individuals suffering from diabetes. Although endocrinologists and diabetes specialists will continue to maintain expertise in this field, it behooves the primary care physician to have a working knowledge of insulin pumps and sensors to ensure optimal clinical care and decision-making for their patients.

Managing diabetes in the digital age

The prevalence of diabetes is rising globally. Poor glucose control results in higher rates of diabetes-related complications and an increase in health care expenditure. Diabetes self-management education (DSME) training has shown to improve glucose control, and thus may reduce long-term complications. Implementation of diabetes self-management education programs may not be feasible for all the institutions or in developing countries due to lack of resources and higher costs associated with DSME training. With the increasing use of smartphones and Internet, there is an opportunity to use digital tools for training people with diabetes to self-manage their disease. A number of mobile applications, Internet portal, and websites are available to help patients to improve their diabetes care. However, the studies are limited to show its effectiveness and cost-benefits in diabetes self-management. In addition, there are many challenges ahead for the digital health industry. In this review, we assess the use of newer technologies and digital health in diabetes self-management with a focus on future directions and potential challenges.

Physical Activity Capture Technology With Potential for Incorporation Into Closed-Loop Control for Type 1 Diabetes

Physical activity is an important determinant of glucose variability in type 1 diabetes (T1D). It has been incorporated as a nonglucose input into closed-loop control (CLC) protocols for T1D during the last 4 years mainly by 3 research groups in single center based controlled clinical trials involving a maximum of 18 subjects in any 1 study. Although physical activity data capture may have clinical benefit in patients with T1D by impacting cardiovascular fitness and optimal body weight achievement and maintenance, limited number of such studies have been conducted to date. Clinical trial registries provide information about a single small sample size 2 center prospective study incorporating physical activity data input to modulate closed-loop control in T1D that are seeking to build on prior studies. We expect an increase in such studies especially since the NIH has expanded support of this type of research with additional grants starting in the second half of 2015. Studies (1) involving patients with other disorders that have lasted 12 weeks or longer and tracked physical activity and (2) including both aerobic and resistance activity may offer insights about the user experience and device optimization even as single input CLC heads into real-world clinical trials over the next few years and nonglucose input is introduced as the next advance.

Faster-acting insulin aspart: earlier onset of appearance and greater early pharmacokinetic and pharmacodynamic effects than insulin aspart

AIMS

To evaluate the pharmacokinetics and pharmacodynamics of faster-acting insulin aspart and insulin aspart in a randomized, single-centre, double-blind study.

METHODS

Fifty-two patients with type 1 diabetes (mean age 40.3 years) received faster-acting insulin aspart, insulin aspart, or another faster aspart formulation (not selected for further development), each as a single 0.2 U/kg subcutaneous dose, under glucose-clamp conditions, in a three-way crossover design (3-12 days washout between dosing).

RESULTS

Faster-acting insulin aspart had a faster onset of exposure compared with insulin aspart, shown by a 57% earlier onset of appearance [4.9 vs 11.2 min; ratio 0.43, 95% confidence interval (CI) 0.36; 0.51], a 35% earlier time to reach 50% maximum concentration (20.7 vs 31.6 min; ratio 0.65, 95% CI 0.59; 0.72) and a greater early exposure within 90 min after dosing. The greatest difference occurred during the first 15 min, when area under the serum insulin aspart curve was 4.5-fold greater with faster-acting insulin aspart than with insulin aspart. Both treatments had a similar time to maximum concentration, total exposure and maximum concentration. Faster-acting insulin aspart had a significantly greater glucose-lowering effect within 90 min after dosing [largest difference: area under the curve for the glucose infusion rate (AUC(GIR), 0-30 min) ratio 1.48, 95% CI 1.13; 2.02] and 17% earlier time to reach 50% maximum glucose infusion rate (38.3 vs 46.1 min; ratio 0.83, 95% CI 0.73; 0.94). The primary endpoint (AUC(GIR, 0-2 h)) was 10% greater for faster-acting insulin aspart, but did not reach statistical significance (ratio 1.10, 95% CI 1.00; 1.22). Both treatments had similar total and maximum glucose-lowering effects, indicating similar overall potency.

CONCLUSIONS

Faster-acting insulin aspart was found to have earlier onset and higher early exposure than insulin aspart, and a greater early glucose-lowering effect, with similar potency.

Glucagon - the new 'insulin' in the pathophysiology of diabetes

PURPOSE OF REVIEW

Autoimmune destruction of the β cells is considered the key abnormality in type 1 diabetes mellitus and insulin replacement the primary therapeutic strategy. However, a lack of insulin is accompanied by disturbances in glucagon release, which is excessive postprandially, but insufficient during hypoglycaemia. In addition, replacing insulin alone appears insufficient for adequate glucose control. This review focuses on the growing body of evidence that glucagon abnormalities contribute significantly to the pathophysiology of diabetes and on recent efforts to target the glucagon axis as adjunctive therapy to insulin replacement.

RECENT FINDINGS

This review discusses recent (since 2013) advances in abnormalities of glucagon regulation and their link to the pathophysiology of diabetes; new mechanisms of glucagon action and regulation; manipulation of glucagon in diabetes treatment; and analytical and systems biology tools to study glucagon regulation.

SUMMARY

Recent efforts 'resurrected' glucagon as a key hormone in the pathophysiology of diabetes. New studies target its abnormal regulation and action that is key for improving diabetes treatment. The progress is promising, but major questions remain, including unravelling the mechanism of loss of glucagon counterregulation in type 1 diabetes mellitus and how best to manipulate glucagon to achieve more efficient and safer glycaemic control.

Closed loop insulin delivery in diabetes

The primary goal of type 1 diabetes treatment is attaining near-normal glucose values. This currently remains out of reach for most people with type 1 diabetes despite intensified insulin treatment in the form of insulin analogues, educational interventions, continuous glucose monitoring, and sensor augmented insulin pump. The main remaining problem is risk of hypoglycaemia, which cannot be sufficiently reduced in all patient groups. Additionally, patients' burn-out often develops with years of tedious day-to-day diabetes management, rendering available diabetes-related technology less efficient. Over the past 40 years, several attempts have been made towards computer-programmed insulin delivery in the form of closed loop, with faster developments especially in the past decade. Automated insulin delivery has reduced human error in glycaemic control and considerably lessened the burden of routine self-management. In this chapter, data from randomized controlled trials with closed-loop insulin delivery that included type 1 diabetes population are summarized, and an evidence-based vision for possible routine utilization of closed loop is provided.

Youth and parent measures of self-efficacy for continuous glucose monitoring: survey psychometric properties

BACKGROUND

This study aimed to describe the development and psychometric evaluation of novel youth and parent measures of self-efficacy related to continuous glucose monitoring (CGM) in pediatric patients with type 1 diabetes. This evaluation also assessed the predictive validity of the CGM Self-Efficacy (CGM-SE) surveys on CGM use and hemoglobin A1c (HbA1c) levels.

SUBJECTS AND METHODS

Study participants included 120 youth with type 1 diabetes for ≥1 year enrolled in a 2-year randomized clinical trial comparing CGM use with and without the addition of a family-focused CGM behavioral intervention. Youth and parents completed the CGM-SE surveys at randomization after a 1-week run-in to assess CGM tolerability. Analyses of predictive validity excluded the intervention group and included 61 youth in the control group in order to assess CGM use and HbA1c outcomes 3 and 6 months after randomization.

RESULTS

At study entry, youth were 12.7±2.7 years old with a diabetes duration of 6.1±3.6 years and an HbA1c level of 8.0±0.8% (64±9 mmol/mol); blood glucose monitoring frequency was 6.8±2.4 times/day, and 84% received pump therapy. CGM-SE surveys had acceptable internal consistency (Cronbach's α=0.80 for youth and 0.82 for parents). Youth reporting higher baseline CGM self-efficacy (CGM-SE score of >80) had significantly greater CGM use and lower HbA1c level after 3 and 6 months compared with youth reporting lower baseline CGM self-efficacy (CGM-SE score of ≤80).

CONCLUSIONS

The CGM-SE surveys appear to have strong psychometric properties. CGM self-efficacy may offer an opportunity to assess the likelihood of CGM adherence and glycemic improvement in youth with type 1 diabetes in clinical and research settings.

Hypo- and Hyperglycemic Alarms: Devices and Algorithms

Soon after the discovery that insulin regulates blood glucose by Banting and Best in 1922, the symptoms and risks associated with hypoglycemia became widely recognized. This article reviews devices to warn individuals of impending hypo- and hyperglycemia; biosignals used by these devices include electroencephalography, electrocardiography, skin galvanic resistance, diabetes alert dogs, and continuous glucose monitors (CGMs). While systems based on other technology are increasing in performance and decreasing in size, CGM technology remains the best method for both reactive and predictive alarming of hypo- or hyperglycemia.

In vivo performance and biocompatibility of a subcutaneous implant for real-time glucose-responsive insulin delivery

An implantable, glucose-responsive insulin delivery microdevice was reported previously by our group, providing rapid insulin release in response to hyperglycemic events and efficacy in vivo over a 1-week period when implanted intraperitoneally in rats with diabetes. Herein, we focused on the improvement of the microdevice prototype for long-term glycemic control by subcutaneous (SC) implantation, which allows for easy retrieval and replacement as needed. To surmount the strong immune response to the SC implant system, the microdevice was treated by surface modification with high-molecular-weight polyethylene glycol (PEG). In vitro glucose-responsive insulin release, in vivo efficacy, and biocompatibility of the microdevice were studied. Modification with 20-kDa PEG chains greatly reduced the immune response without a significant change in glucose-responsive insulin release in vitro. The fibrous capsule thickness was reduced from approximately 1,000 μm for the untreated devices to 30-300 μm for 2-kDa PEG-treated and to 30-50 μm for 20-kDa PEG-treated devices after 30 days of implantation. The integrity of the glucose-responsive bioinorganic membrane and the resistance to acute and chronic immune response were improved with the long-chain 20-kDa PEG brush layer. The 20-kDa PEG-treated microdevice provided long-term maintenance of euglycemia in a rat model of diabetes for up to 18 days. Moreover, a consistent rapid response to short-term glucose challenge was demonstrated in multiple-day tests for the first time on rats with diabetes in which the devices were implanted. The improvement of the microdevice is a promising step toward a long-acting insulin implant system for a true, closed-loop treatment of diabetes.