The Association Between Diet Quality and Glycemic Outcomes Among People with Type 1 Diabetes.

Background: The amount and type of food consumed impacts the glycemic response and insulin needs of people with type 1 diabetes mellitus (T1DM). Daily variability in consumption, reflected in diet quality, may acutely impact glycemic levels and insulin needs. Objective: Type 1 Diabetes Exercise Initiative (T1DEXI) data were examined to evaluate the impact of daily diet quality on near-term glycemic control and interaction with exercise. Methods: Using the Remote Food Photography Method, ≤8 d of dietary intake data were analyzed per participant. Diet quality was quantified with the Healthy Eating Index-2015 (HEI), where a score of 100 indicates the highest-quality diet. Each participant day was classified as low HEI (≤57) or high HEI (>57) based on the mean of nationally reported HEI data. Within participants, the relationship between diet quality and subsequent glycemia measured by continuous glucose monitoring (CGM) and total insulin dose usage was evaluated using a paired t-test and robust regression models. Results: Two hundred twenty-three adults (76% female) with mean ± SD age, HbA1c, and body mass index (BMI) of 37 ± 14 y, 6.6% ± 0.7%, and 25.1 ± 3.6 kg/m2, respectively, were included in these analyses. The mean HEI score was 56 across all participant days. On high HEI days (mean, 66 ± 4) compared with low HEI days (mean, 47 ± 5), total time in range (70-180 mg/dL) was greater (77.2% ± 14% compared with 75.7% ± 14%, respectively, P = 0.01), whereas time above 180 mg/dL (19% ± 14% compared with 21% ± 15%, respectively, P = 0.004), mean glucose (143 ± 22 compared with 145 ± 22 mg/dL, respectively, P = 0.02), and total daily insulin dose (0.52 ± 0.18 compared with 0.54 ± 0.18 U/kg/d, respectively, P = 0.009) were lower. The interaction between diet quality and exercise on glycemia was not significant. Conclusions: Higher HEI scores correlated with improved glycemia and lower insulin needs, although the impact of diet quality was modest and smaller than the previously reported impact of exercise.

Risk factors associated with cognitive performance and cognitive impairment in older adults with type 1 diabetes: Data from the Wireless Innovation for Seniors with Diabetes Mellitus (WISDM) study.

BACKGROUND: Adults with type 1 diabetes (T1D) are considered at increased risk for cognitive impairment and accelerated brain aging. However, longitudinal data on cognitive impairment and dementia in this population are scarce. OBJECTIVE: To identify risk factors associated with cognitive performance and cognitive impairment in a longitudinal sample of older adults with T1D. METHODS: We analyzed data collected as part of the Wireless Innovation for Seniors with Diabetes Mellitus (WISDM) Study, in which 22 endocrinology practices participated. Randomized participants with T1D ≥60 years of age who completed at least one cognitive assessment were included in this study (n = 203). Cognitive impairment was classified using published recommendations. RESULTS: Older age, male sex, non-private health insurance, worse daily functioning, diagnosis of neuropathy, and longer duration of diabetes were associated with worse cognitive performance, but not cognitive impairment. 49 % and 39 % of the sample met criteria for cognitive impairment at baseline and 52 weeks respectively. Of the participants that had data at both time points, 10 % were normal at baseline and impaired at 52 weeks and 22 % of participants (44 % of those classified with cognitive impairment at baseline) reverted to normal over 52 weeks. CONCLUSION: This study indicated that several demographic and clinical characteristics are associated with worse cognitive performance in older adults with T1D, but there were no associations between these characteristics and cognitive impairment defined by NIH Toolbox cognitive impairment criteria. Caution is warranted when assessing cognition in older adults with T1D, as a large percentage of those identified as having cognitive impairment at baseline reverted to normal after 52 weeks. There is need for future studies on the interrelationship of cognition and aging to better understand the effects of T1D on cognitive health, to improve clinical monitoring and help mitigate the risk of dementia in this population.

Early-phase insulin secretion during mixed-meal tolerance testing predicts ß-cell function and secretory capacity in cystic fibrosis.

Insulin secretion within 30 minutes of nutrient ingestion is reduced in people with cystic fibrosis (PwCF) and pancreatic insufficiency and declines with worsening glucose tolerance. The glucose potentiated arginine (GPA) test is validated for quantifying ß-cell secretory capacity as an estimate of functional ß-cell mass but requires technical expertise and is burdensome. This study sought to compare insulin secretion during mixed-meal tolerance testing (MMTT) to GPA-derived parameters in PwCF. Methods: Secondary data analysis of CF-focused prospective studies was performed in PwCF categorized as 1) pancreatic insufficient [PI-CF] or 2) pancreatic sufficient [PS-CF] and in 3) non-CF controls. MMTT: insulin secretory rates (ISR) were derived by parametric deconvolution using 2-compartment model of C-peptide kinetics, and incremental area under the curve (AUC) was calculated for 30, 60 and 180-minutes. GPA: acute insulin (AIR) and C-peptide responses (ACR) were calculated as average post-arginine insulin or C-peptide response minus pre-arginine insulin or C-peptide under fasting (AIRarg and ACRarg), ~230 mg/dL (AIRpot and ACRpot), and ~340 mg/dL (AIRmax and ACRmax) hyperglycemic clamp conditions. Relationships of MMTT to GPA parameters were derived using Pearson's correlation coefficient. Predicted values were generated for MMTT ISR and compared to GPA parameters using Bland Altman analysis to assess degree of concordance. Results: 85 PwCF (45 female; 75 PI-CF and 10 PS-CF) median (range) age 23 (6-56) years with BMI 23 (13-34) kg/m2, HbA1c 5.5 (3.8-10.2)%, and FEV1%-predicted 88 (26-125) and 4 non-CF controls of similar age and BMI were included. ISR AUC30min positively correlated with AIRarg (r=0.55), AIRpot (r=0.62), and AIRmax (r=0.46) and with ACRarg (r=0.59), ACRpot (r=0.60), and ACRmax (r=0.51) (all P<0.001). ISR AUC30min strongly predicted AIRarg (concordance=0.86), AIRpot (concordance=0.89), and AIRmax (concordance=0.76) at lower mean GPA values, but underestimated AIRarg, AIRpot, and AIRmax at higher GPA-defined ß-cell secretory capacity. Between test agreement was unaltered by adjustment for study group, OGTT glucose category, and BMI. Conclusion: Early-phase insulin secretion during MMTT can accurately predict GPA-derived measures of ß-cell function and secretory capacity when functional ß-cell mass is reduced. These data can inform future multicenter studies requiring reliable, standardized, and technically feasible testing mechanisms to quantify ß-cell function and secretory capacity.

Factors Affecting Reproducibility of Change in Glucose During Exercise: Results From the Type 1 Diabetes and EXercise Initiative.

AIMS: To evaluate factors affecting within-participant reproducibility in glycemic response to different forms of exercise. METHODS: Structured exercise sessions ~30 minutes in length from the Type 1 Diabetes Exercise Initiative (T1DEXI) study were used to assess within-participant glycemic variability during and after exercise. The effect of several pre-exercise factors on the within-participant glycemic variability was evaluated. RESULTS: Data from 476 adults with type 1 diabetes were analyzed. A participant's change in glucose during exercise was reproducible within 15 mg/dL of the participant's other exercise sessions only 32% of the time. Participants who exercised with lower and more consistent glucose level, insulin on board (IOB), and carbohydrate intake at exercise start had less variability in glycemic change during exercise. Participants with lower mean glucose (P < .001), lower glucose coefficient of variation (CV) (P < .001), and lower % time <70 mg/dL (P = .005) on sedentary days had less variable 24-hour post-exercise mean glucose. CONCLUSIONS: Reproducibility of change in glucose during exercise was low in this cohort of adults with T1D, but more consistency in pre-exercise glucose levels, IOB, and carbohydrates may increase this reproducibility. Mean glucose variability in the 24 hours after exercise is influenced more by the participant's overall glycemic control than other modifiable factors.

Impact of impaired awareness of hypoglycemia on glucose decline during and after exercise in T1D: The T1DEXI Study.

OBJECTIVE: To assess whether impaired awareness of hypoglycemia (IAH) affects exercise-associated hypoglycemia in adults with type 1 diabetes (T1D). METHODS: We compared continuous glucose monitoring (CGM)-measured glucose during exercise and for 24-hours following exercise from 95 adults with T1D and IAH (Clarke score ≥4 or ≥1 severe hypoglycemic event within the past year) to 95 'Aware' adults (Clarke score ≤2 and no severe hypoglycemic event within the past year) matched on sex, age, insulin delivery modality, and HbA1c. A total of 4,236 exercise sessions, and 1,794 exercise days and 839 sedentary days, defined as 24-hours following exercise or a day without exercise, respectively, were available for analysis. RESULTS: Participants with IAH exhibited a non-significant trend towards greater decline in glucose during exercise compared to 'Aware' (-21 ± 44 vs. -19 ± 43 mg/dL [-1.17 ± 2.44 vs. -1.05 ± 2.39 mmol/L], adjusted group difference of -4.2 [95% CI: -8.4 to 0.05] mg/dL [-0.23 95% CI: -0.47 to 0.003 mmol/L], P = 0.051). Individuals with IAH had higher proportion of days with hypoglycemic events <70 mg/dL[3.89 mmol/L] (≥15 minutes <70 mg/dL[<3.89 mmol/L]) both on exercise days (51% vs. 43%, P = 0.006) and sedentary days (48% vs. 30%, P = 0.001). The increased odds of experiencing a hypoglycemic event <70 mg/dL[<3.89 mmol/L] for individuals with IAH compared to 'Aware' did not differ significantly between exercise and sedentary days (interaction P = 0.36). CONCLUSION: Individuals with IAH have a higher underlying risk of hypoglycemia than 'Aware' individuals. Exercise does not appear to differentially increase risk for hypoglycemia during the activity, or in the subsequent 24-hours for IAH compared to Aware individuals with T1D.

Associations between daily step count classifications and continuous glucose monitoring metrics in adults with type 1 diabetes: analysis of the Type 1 Diabetes Exercise Initiative (T1DEXI) cohort.

AIMS/HYPOTHESIS: Adults with type 1 diabetes should perform daily physical activity to help maintain health and fitness, but the influence of daily step counts on continuous glucose monitoring (CGM) metrics are unclear. This analysis used the Type 1 Diabetes Exercise Initiative (T1DEXI) dataset to investigate the effect of daily step count on CGM-based metrics. METHODS: In a 4 week free-living observational study of adults with type 1 diabetes, with available CGM and step count data, we categorised participants into three groups-below (<7000), meeting (7000-10,000) or exceeding (>10,000) the daily step count goal-to determine if step count category influenced CGM metrics, including per cent time in range (TIR: 3.9-10.0 mmol/l), time below range (TBR: <3.9 mmol/l) and time above range (TAR: >10.0 mmol/l). RESULTS: A total of 464 adults with type 1 diabetes (mean±SD age 37±14 years; HbA1c 48.8±8.1 mmol/mol [6.6±0.7%]; 73% female; 45% hybrid closed-loop system, 38% standard insulin pump, 17% multiple daily insulin injections) were included in the study. Between-participant analyses showed that individuals who exceeded the mean daily step count goal over the 4 week period had a similar TIR (75±14%) to those meeting (74±14%) or below (75±16%) the step count goal (p>0.05). In the within-participant comparisons, TIR was higher on days when the step count goal was exceeded or met (both 75±15%) than on days below the step count goal (73±16%; both p<0.001). The TBR was also higher when individuals exceeded the step count goals (3.1%±3.2%) than on days when they met or were below step count goals (difference in means -0.3% [p=0.006] and -0.4% [p=0.001], respectively). The total daily insulin dose was lower on days when step count goals were exceeded (0.52±0.18 U/kg; p<0.001) or were met (0.53±0.18 U/kg; p<0.001) than on days when step counts were below the current recommendation (0.55±0.18 U/kg). Step count had a larger effect on CGM-based metrics in participants with a baseline HbA1c ≥53 mmol/mol (≥7.0%). CONCLUSIONS/INTERPRETATION: Our results suggest that, compared with days with low step counts, days with higher step counts are associated with slight increases in both TIR and TBR, along with small reductions in total daily insulin requirements, in adults living with type 1 diabetes. DATA AVAILABILITY: The data that support the findings reported here are available on the Vivli Platform (ID: T1-DEXI; https://doi.org/10.25934/PR00008428 ).

Evidence for C-peptide as a Validated Surrogate to Predict Clinical Benefits in Trials of Disease-Modifying Therapies for Type 1 Diabetes.

Type 1 diabetes is a chronic autoimmune disease in which destruction of pancreatic beta cells causes life-threatening metabolic dysregulation. Numerous approaches are envisioned for new therapies, but limitations of current clinical outcome measures are significant disincentives to development efforts. C-peptide, a direct byproduct of proinsulin processing, is a quantitative biomarker of beta cell function that is not cleared by the liver and can be measured in the peripheral blood. Studies of quantitative measures of beta cell function have established a predictive relationship between stimulated C-peptide as a measure of beta cell function and clinical benefits. C-peptide levels at diagnosis are often high enough to afford glycemic control benefits associated with protection from end-organ complications of diabetes, and even lower levels offer protection from severe hypoglycemia in type 1 diabetes, as observed in large prospective cohort studies and interventional trials of islet transplantation. These observations support consideration of C-peptide not just as a biomarker of beta cell function, but also as a specific, sensitive, feasible, and clinically meaningful outcome defining beta cell preservation or restoration for clinical trials of disease-modifying therapies. Regulatory acceptance of C-peptide as a validated surrogate for demonstration of efficacy would greatly facilitate development of disease-modifying therapies for type 1 diabetes.

Characterization of impaired beta and alpha cell function in response to an oral glucose challenge in cystic fibrosis: a cross-sectional study.

Aims: The purpose of the study was to further elucidate the pathophysiology of cystic fibrosis (CF)-related diabetes (CFRD) and potential drivers of hypoglycaemia. Hence, we aimed to describe and compare beta cell function (insulin and proinsulin) and alpha cell function (glucagon) in relation to glucose tolerance in adults with CF and to study whether hypoglycaemia following oral glucose challenge may represent an early sign of islet cell impairment. Methods: Adults with CF (≥18 years) were included in a cross-sectional study using an extended (-10, -1, 10, 20, 30, 45, 60, 90, 120, 150, and 180 min) or a standard (-1, 30, 60, and 120 min) oral glucose tolerance test (OGTT). Participants were classified according to glucose tolerance status and hypoglycaemia was defined as 3-hour glucose <3.9 mmol/L in those with normal glucose tolerance (NGT) and early glucose intolerance (EGI). Results: Among 93 participants, 67 underwent an extended OGTT. In addition to worsening in insulin secretion, the progression to CFRD was associated with signs of beta cell stress, as the fasting proinsulin-to-insulin ratio incrementally increased (p-value for trend=0.013). The maximum proinsulin level (pmol/L) was positively associated with the nadir glucagon, as nadir glucagon increased 6.2% (95% confidence interval: 1.4-11.3%) for each unit increase in proinsulin. Those with hypoglycaemia had higher 60-min glucose, 120-min C-peptide, and 180-min glucagon levels (27.8% [11.3-46.7%], 42.9% [5.9-92.85%], and 80.3% [14.9-182.9%], respectively) and unaltered proinsulin-to-insulin ratio compared to those without hypoglycaemia. Conclusions: The maximum proinsulin concentration was positively associated with nadir glucagon during the OGTT, suggesting that beta cell stress is associated with abnormal alpha cell function in adults with CF. In addition, hypoglycaemia seemed to be explained by a temporal mismatch between glucose and insulin levels rather than by an impaired glucagon response.

Validating and Establishing a Diagnostic Threshold for the Hypoglycemia Awareness Questionnaire Impaired Awareness Subscale.

OBJECTIVE: To evaluate the discriminant and convergent validities of the Hypoglycemia Awareness Questionnaire Impaired Awareness (HypoA-Q IA) subscale and establish a diagnostic threshold for the classification of impaired awareness of hypoglycemia (IAH) in adults with type 1 diabetes (T1D). METHODS: Twenty-one adults with T1D (male, 48%; median age, 36 years; and T1D duration, 21 years) completed the HypoA-Q IA subscale, Clarke, and hypoglycemia severity (HYPO) scores, continuous glucose monitoring, and hyperinsulinemic hypoglycemic clamp testing. Those with IAH defined by a Clarke score of ≥4 (n = 10) and who experienced severely problematic hypoglycemia and/or marked glycemic lability started automated insulin delivery as part of an 18-month intervention study with the 6-monthly paired assessment of the HypoA-Q IA subscale, Clarke score, HYPO score and continuous glucose monitoring, and hypoglycemic clamp testing at baseline and 6 and 18 months. RESULTS: The HypoA-Q IA subscale discriminated between those with and without IAH defined by the Clarke score (W = 110.5; P <.001). During intervention, the HypoA-Q IA subscale demonstrated convergent validity via significant relationships with the Clarke (r = 0.72; P <.001) and HYPO (r = 0.60; P <.001) scores; hypoglycemia exposure below 70 (r = 0.53; P <.01), 60 (r = 0.50; P <.01), and 54 (r = 0.48; P <.01) mg/dL; and autonomic symptom (r = -0.53; P <.05), epinephrine (r = -0.68; P <.001), and pancreatic polypeptide (r = -0.52; P <.05) responses to insulin-induced hypoglycemia. The receiver operating characteristic curve analysis revealed that the HypoA-Q IA subscale was an excellent predictor of an abnormal symptom response to insulin-induced hypoglycemia (area under the curve, 0.86) with a score of 12, which was the optimal threshold for IAH classification (sensitivity, 83%; specificity, 80%). CONCLUSION: These findings support the validity of the HypoA-Q IA subscale and propose a HypoA-Q IA diagnostic threshold to identify IAH in both clinical and research settings.

Prolonged Use of an Automated Insulin Delivery System Improves Sleep in Long-Standing Type 1 Diabetes Complicated by Impaired Awareness of Hypoglycemia.

BACKGROUND: This study assessed changes in actigraphy-estimated sleep and glycemic outcomes after initiating automated insulin delivery (AID). METHODS: Ten adults with long-standing type 1 diabetes and impaired awareness of hypoglycemia (IAH) participated in an 18-month clinical trial assessing an AID intervention on hypoglycemia and counter-regulatory mechanisms. Data from eight participants (median age = 58 years) with concurrent wrist actigraph and continuous glucose monitoring (CGM) data were used in the present analyses. Actigraphs and CGM measured sleep and glycemic control at baseline (one week) and months 3, 6, 9, 12, 15, and 18 (three weeks) following AID initiation. HypoCount software integrated actigraphy with CGM data to separate wake and sleep-associated glycemic measures. Paired sample t-tests and Cohen's d effect sizes modeled changes and their magnitude in sleep, glycemic control, IAH (Clarke score), hypoglycemia severity (HYPO score), hypoglycemia exposure (CGM), and glycemic variability (lability index [LI]; CGM coefficient-of-variation [CV]) from baseline to 18 months. RESULTS: Sleep improved from baseline to 18 months (shorter sleep latency [P < .05, d = 1.74], later sleep offset [P < .05, d = 0.90], less wake after sleep onset [P < .01, d = 1.43]). Later sleep onset (d = 0.74) and sleep midpoint (d = 0.77) showed medium effect sizes. Sleep improvements were evident from 12 to 15 months after AID initiation and were preceded by improved hypoglycemia awareness (Clarke score [d = 1.18]), reduced hypoglycemia severity (HYPO score [d = 2.13]), reduced sleep-associated hypoglycemia (percent time glucose was < 54 mg/dL, < 60 mg/dL,< 70 mg/dL; d = 0.66-0.81), and reduced glucose variability (LI, d = 0.86; CV, d = 0.62). CONCLUSION: AID improved sleep initiation and maintenance. Improved awareness of hypoglycemia, reduced hypoglycemia severity, hypoglycemia exposure, and glucose variability preceded sleep improvements.This trial is registered with ClinicalTrials.gov NCT03215914 https://clinicaltrials.gov/ct2/show/NCT03215914.

Preservation of ß-cell Function in Pancreatic Insufficient Cystic Fibrosis With Highly Effective CFTR Modulator Therapy.

CONTEXT: Elexacaftor/tezacaftor/ivacaftor (ETI; Trikafta) enhances aberrant cystic fibrosis transmembrane conductance regulator function and may improve the insulin secretory defects associated with a deterioration in clinical outcomes in pancreatic insufficient cystic fibrosis (PI-CF). OBJECTIVE: This longitudinal case-control study assessed changes in ß-cell function and secretory capacity measures over 2 visits in individuals with PI-CF who were initiated on ETI after the baseline visit (2012-2018) and (1) restudied between 2019 and 2021 (ETI group) vs (2) those restudied between 2015 and 2018 and not yet treated with cystic fibrosis transmembrane conductance regulator modulator therapy (controls). METHODS: Nine ETI participants (mean ± SD age, 25 ± 5 years) and 8 matched controls were followed up after a median (interquartile range) 5 (4-7) and 3 (2-3) years, respectively (P < .01), with ETI initiation a median of 1 year before follow-up. Clinical outcomes, glucose-potentiated arginine, and mixed-meal tolerance test measures were assessed with comparisons of within- and between-group change by nonparametric testing. RESULTS: Glucose-potentiated insulin and C-peptide responses to glucose-potentiated arginine deteriorated in controls but not in the ETI group, with C-peptide changes different between groups (P < .05). Deterioration in basal proinsulin secretory ratio was observed in controls but improved, as did the maximal arginine-induced proinsulin secretory ratio, in the ETI group (P < .05 for all comparisons). During mixed-meal tolerance testing, early insulin secretion improved as evidenced by more rapid insulin secretory rate kinetics. CONCLUSION: ETI preserves ß-cell function in CF through effects on glucose-dependent insulin secretion, proinsulin processing, and meal-related insulin secretion. Further work should determine whether early intervention with ETI can prevent deterioration of glucose tolerance in PI-CF.

The Type 1 Diabetes and EXercise Initiative: Predicting Hypoglycemia Risk During Exercise for Participants with Type 1 Diabetes Using Repeated Measures Random Forest.

Objective: Exercise is known to increase the risk for hypoglycemia in type 1 diabetes (T1D) but predicting when it may occur remains a major challenge. The objective of this study was to develop a hypoglycemia prediction model based on a large real-world study of exercise in T1D. Research Design and Methods: Structured study-specified exercise (aerobic, interval, and resistance training videos) and free-living exercise sessions from the T1D Exercise Initiative study were used to build a model for predicting hypoglycemia, a continuous glucose monitoring value <70 mg/dL, during exercise. Repeated measures random forest (RMRF) and repeated measures logistic regression (RMLR) models were constructed to predict hypoglycemia using predictors at the start of exercise and baseline characteristics. Models were evaluated with area under the receiver operating characteristic curve (AUC) and balanced accuracy. Results: RMRF and RMLR had similar AUC (0.833 vs. 0.825, respectively) and both models had a balanced accuracy of 77%. The probability of hypoglycemia was higher for exercise sessions with lower pre-exercise glucose levels, negative pre-exercise glucose rates of change, greater percent time <70 mg/dL in the 24 h before exercise, and greater pre-exercise bolus insulin-on-board (IOB). Free-living aerobic exercises, walking/hiking, and physical labor had the highest probability of hypoglycemia, while structured exercises had the lowest probability of hypoglycemia. Conclusions: RMRF and RMLR accurately predict hypoglycemia during exercise and identify factors that increase the risk of hypoglycemia. Lower glucose, decreasing levels of glucose before exercise, and greater pre-exercise IOB largely predict hypoglycemia risk in adults with T1D.

Cystic Fibrosis-Related Diabetes Workshop: Research Priorities Spanning Disease Pathophysiology, Diagnosis, and Outcomes.

Cystic fibrosis (CF) is a recessive disorder arising from mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR is expressed in numerous tissues, with high expression in the airways, small and large intestine, pancreatic and hepatobiliary ducts, and male reproductive tract. CFTR loss in these tissues disrupts regulation of salt, bicarbonate, and water balance across their epithelia, resulting in a systemic disorder with progressive organ dysfunction and damage. Pancreatic exocrine damage ultimately manifests as pancreatic exocrine insufficiency that begins as early as infancy. Pancreatic remodeling accompanies this early damage, during which abnormal glucose tolerance can be observed in toddlers. With increasing age, however, insulin secretion defects progress such that CF-related diabetes (CFRD) occurs in 20% of teens and up to half of adults with CF. The relevance of CFRD is highlighted by its association with increased morbidity, mortality, and patient burden. While clinical research on CFRD has greatly assisted in the care of individuals with CFRD, key knowledge gaps on CFRD pathogenesis remain. Furthermore, the wide use of CFTR modulators to restore CFTR activity is changing the CFRD clinical landscape and the field's understanding of CFRD pathogenesis. For these reasons, the National Institute of Diabetes and Digestive and Kidney Diseases and the Cystic Fibrosis Foundation sponsored a CFRD Scientific Workshop, 23-25 June 2021, to define knowledge gaps and needed research areas. This article describes the findings from this workshop and plots a path for CFRD research that is needed over the next decade.

Cystic Fibrosis-Related Diabetes Workshop: Research Priorities Spanning Disease Pathophysiology, Diagnosis, and Outcomes.

Cystic fibrosis (CF) is a recessive disorder arising from mutations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR) protein. CFTR is expressed in numerous tissues, with high expression in the airways, small and large intestine, pancreatic and hepatobiliary ducts, and male reproductive tract. CFTR loss in these tissues disrupts regulation of salt, bicarbonate, and water balance across their epithelia, resulting in a systemic disorder with progressive organ dysfunction and damage. Pancreatic exocrine damage ultimately manifests as pancreatic exocrine insufficiency that begins as early as infancy. Pancreatic remodeling accompanies this early damage, during which abnormal glucose tolerance can be observed in toddlers. With increasing age, however, insulin secretion defects progress such that CF-related diabetes (CFRD) occurs in 20% of teens and up to half of adults with CF. The relevance of CFRD is highlighted by its association with increased morbidity, mortality, and patient burden. While clinical research on CFRD has greatly assisted in the care of individuals with CFRD, key knowledge gaps on CFRD pathogenesis remain. Furthermore, the wide use of CFTR modulators to restore CFTR activity is changing the CFRD clinical landscape and the field's understanding of CFRD pathogenesis. For these reasons, the National Institute of Diabetes and Digestive and Kidney Diseases and the Cystic Fibrosis Foundation sponsored a CFRD Scientific Workshop, 23-25 June 2021, to define knowledge gaps and needed research areas. This article describes the findings from this workshop and plots a path for CFRD research that is needed over the next decade.

Association between primary graft function and 5-year outcomes of islet allogeneic transplantation in type 1 diabetes: a retrospective, multicentre, observational cohort study in 1210 patients from the Collaborative Islet Transplant Registry.

BACKGROUND: Allogeneic islet transplantation is a validated therapy in type 1 diabetes; however, there is decline of transplanted islet graft function over time and the mechanisms underlying this decline are unclear. We evaluated the distinct association between primary graft function (PGF) and 5-year islet transplantation outcomes. METHODS: In this retrospective, multicentre, observational cohort study, we enrolled all patients from the Collaborative Islet Transplant Registry who received islet transplantation alone (ITA recipients) or islet-after-kidney transplantation (IAK recipients) between Jan 19, 1999, and July 17, 2020, with a calculable PGF (exposure of interest), measured 28 days after last islet infusion with a validated composite index of islet graft function (BETA-2 score). The primary outcome was cumulative incidence of unsuccessful islet transplantation, defined as an HbA1c of 7·0% (53 mmol/mol) or higher, or severe hypoglycaemia (ie, requiring third-party intervention to correct), or a fasting C-peptide concentration of less than 0·2 ng/mL. Secondary outcomes were graft exhaustion (fasting C-peptide <0·3 ng/mL); inadequate glucose control (HbA1c ≥7·0% [53 mmol/mol] or severe hypoglycaemia); and requirement for exogenous insulin therapy (≥14 consecutive days). Associations between PGF and islet transplantation outcomes were explored with a competing risk analysis adjusted for all covariates suspected or known to affect outcomes. A predictive model based on PGF was built and internally validated by using bootstraps resampling method. FINDINGS: In 39 centres worldwide, we enrolled 1210 patients with a calculable PGF (of those without missing data, mean age 47 years [SD 10], 712 [59·5%] were female, and 865 (97·9%) were White), who received a median of 10·8 thousand islet-equivalents per kg of bodyweight (IQR 7·4-13·5). 986 (82·4%) were ITA recipients and 211 (17·6%) were IAK recipients. Of 1210 patients, 452 (37·4%) received a single islet infusion and 758 (62·6%) received multiple islet infusions. Mean PGF was 14·3 (SD 8·8). The 5-year cumulative incidence of unsuccessful islet transplantation was 70·7% (95% CI 67·2-73·9), and was inversely and linearly related to PGF, with an adjusted subhazard ratio (sHR) of 0·77 (95% CI 0·72-0·82) per 5-unit increase of BETA-2 score (p<0·0001). Secondary endpoints were similarly related to PGF. The model-adjusted median C-statistic values of PGF for predicting 5-year cumulative incidences of unsuccessful islet transplantation, graft exhaustion, inadequate glucose control, and exogenous insulin therapy were 0·70 (range 0·69-0·71), 0·76 (0·74-0·77), 0·65 (0·64-0·66), and 0·72 (0·71-0·73), respectively. INTERPRETATION: This global multicentre study reports a linear and independent association between PGF and 5-year clinical outcomes of islet transplantation. The main study limitations are its retrospective design and the absence of analysis of complications. FUNDING: Public Health Service Research, National Institutes of Health, Juvenile Diabetes Research Foundation International, Agence National de la Recherche, Fondation de l'Avenir, and Fonds de Dotation Line Renaud-Loulou Gasté.

Examining the Acute Glycemic Effects of Different Types of Structured Exercise Sessions in Type 1 Diabetes in a Real-World Setting: The Type 1 Diabetes and Exercise Initiative (T1DEXI).

OBJECTIVE: Maintenance of glycemic control during and after exercise remains a major challenge for individuals with type 1 diabetes. Glycemic responses to exercise may differ by exercise type (aerobic, interval, or resistance), and the effect of activity type on glycemic control after exercise remains unclear. RESEARCH DESIGN AND METHODS: The Type 1 Diabetes Exercise Initiative (T1DEXI) was a real-world study of at-home exercise. Adult participants were randomly assigned to complete six structured aerobic, interval, or resistance exercise sessions over 4 weeks. Participants self-reported study and nonstudy exercise, food intake, and insulin dosing (multiple daily injection [MDI] users) using a custom smart phone application and provided pump (pump users), heart rate, and continuous glucose monitoring data. RESULTS: A total of 497 adults with type 1 diabetes (mean age ± SD 37 ± 14 years; mean HbA1c ± SD 6.6 ± 0.8% [49 ± 8.7 mmol/mol]) assigned to structured aerobic (n = 162), interval (n = 165), or resistance (n = 170) exercise were analyzed. The mean (± SD) change in glucose during assigned exercise was -18 ± 39, -14 ± 32, and -9 ± 36 mg/dL for aerobic, interval, and resistance, respectively (P < 0.001), with similar results for closed-loop, standard pump, and MDI users. Time in range 70-180 mg/dL (3.9-10.0 mmol/L) was higher during the 24 h after study exercise when compared with days without exercise (mean ± SD 76 ± 20% vs. 70 ± 23%; P < 0.001). CONCLUSIONS: Adults with type 1 diabetes experienced the largest drop in glucose level with aerobic exercise, followed by interval and resistance exercise, regardless of insulin delivery modality. Even in adults with well-controlled type 1 diabetes, days with structured exercise sessions contributed to clinically meaningful improvement in glucose time in range but may have slightly increased time below range.

Automated Insulin Delivery for Hypoglycemia Avoidance and Glucose Counterregulation in Long-Standing Type 1 Diabetes with Hypoglycemia Unawareness.

Objective: Automated insulin delivery (AID) may benefit individuals with long-standing type 1 diabetes where frequent exposure to hypoglycemia impairs counterregulatory responses. This study assessed the effect of 18 months AID on hypoglycemia avoidance and glucose counterregulatory responses to insulin-induced hypoglycemia in long-standing type 1 diabetes complicated by impaired awareness of hypoglycemia. Methods: Ten participants mean ± standard deviation age 49 ± 16 and diabetes duration 34 ± 16 years were initiated on AID. Continuous glucose monitoring was paired with actigraphy to assess awake- and sleep-associated hypoglycemia exposure every 3 months. Hyperinsulinemic hypoglycemic clamp experiments were performed at baseline, 6, and 18 months postintervention. Hypoglycemia exposure was reduced by 3 months, especially during sleep, with effects sustained through 18 months (P ≤ 0.001) together with reduced glucose variability (P < 0.01). Results: Hypoglycemia awareness and severity scores improved (P < 0.01) with severe hypoglycemia events reduced from median (interquartile range) 3 (3-10) at baseline to 0 (0-1) events/person·year postintervention (P = 0.005). During the hypoglycemic clamp experiments, no change was seen in the endogenous glucose production (EGP) response, however, peripheral glucose utilization during hypoglycemia was reduced following intervention [pre: 4.6 ± 0.4, 6 months: 3.8 ± 0.5, 18 months: 3.4 ± 0.3 mg/(kg·min), P < 0.05]. There were increases over time in pancreatic polypeptide (Pre:62 ± 29, 6 months:127 ± 44, 18 months:176 ± 58 pmol/L, P < 0.01), epinephrine (Pre: 199 ± 53, 6 months: 332 ± 91, 18 months: 386 ± 95 pg/mL, P = 0.001), and autonomic symptom (Pre: 6 ± 2, 6 months: 6 ± 2, 18 months: 10 ± 2, P < 0.05) responses. Conclusions: AID led to a sustained reduction of hypoglycemia exposure. EGP in response to insulin-induced hypoglycemia remained defective, however, partial recovery of glucose counterregulation was evidenced by a reduction in peripheral glucose utilization likely mediated by increased epinephrine secretion and, together with improved autonomic symptoms, may contribute to the observed clinical reduction in hypoglycemia.

Predictive Value of C-Peptide Measures for Clinical Outcomes of ß-Cell Replacement Therapy in Type 1 Diabetes: Report From the Collaborative Islet Transplant Registry (CITR).

OBJECTIVE: To determine C-peptide measures and levels associated with positive glycemic control outcomes following islet transplant (ITx) in type 1 diabetes. RESEARCH DESIGN AND METHODS: We evaluated Collaborative Islet Transplant Registry (CITR) islet-alone recipients with pretransplant C-peptide <0.1 nmol/L and mean follow-up of 4.6 ± 1.1 years (n = 677). Receiver operating characteristic area under the curve (ROC-AUC) was used to evaluate the predictive value of fasting and stimulated glucose and C-peptide measures for seven primary outcomes: 1) absence of severe hypoglycemic events (ASHEs); 2) HbA1c <7.0%; 3) HbA1c <7.0% and ASHEs; 4) HbA1c ≤6.5%; 5) HbA1c ≤6.5% and ASHEs; 6) insulin independence; and 7) ASHEs, HbA1c ≤6.5%, and insulin independence (the optimal outcome). Measures with the highest ROC-AUC were selected for determination of optimal cut points. RESULTS: Fasting C-peptide was highly predictive for ASHE (ROC-AUC 0.906; optimal cut point 0.070 nmol/L) and the optimal outcome (ROC-AUC 0.845; optimal cut point 0.33 nmol/L). Mixed-meal tolerance test (MMTT)-stimulated C-peptide-to-glucose ratio (CPGR) outperformed both fasting and stimulated C-peptide for all outcomes except ASHE. The optimal cut point for the optimal outcome was 0.12 nmol/mmol for MMTT-stimulated CPGR and 0.97 nmol/L for MMTT-stimulated C-peptide. CONCLUSIONS: Fasting C-peptide reliably predicts ITx primary outcomes. MMTT-stimulated CPGR provides marginally better prediction for composite ITx outcomes, including insulin independence. In the absence of an MMTT, a fasting C-peptide ≥0.33 nmol/L is a reassuring measure of optimal islet graft function. C-peptide targets represent excellent and easily determinable means to predict glycemic control outcomes after ITx and should be considered as potential goals of ß-cell replacement.