Random non-fasting C-peptide: bringing robust assessment of endogenous insulin secretion to the clinic

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 β-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 β-cell function that is not cleared by the liver and can be measured in the peripheral blood. Studies of quantitative measures of β-cell function have established a predictive relationship between stimulated C-peptide as a measure of β-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 β-cell function but also as a specific, sensitive, feasible, and clinically meaningful outcome defining β-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.

ARTICLE HIGHLIGHTS

Diabetes Study of Children of Diverse Ethnicity and Race: Study design

AIMS

Determining diabetes type in children has become increasingly difficult due to an overlap in typical characteristics between type 1 diabetes (T1D) and type 2 diabetes (T2D). The Diabetes Study in Children of Diverse Ethnicity and Race (DISCOVER) programme is a National Institutes of Health (NIH)-supported multicenter, prospective, observational study that enrols children and adolescents with non-secondary diabetes. The primary aim of the study was to develop improved models to differentiate between T1D and T2D in diverse youth.

MATERIALS AND METHODS

The proposed models will evaluate the utility of three existing T1D genetic risk scores in combination with data on islet autoantibodies and other parameters typically available at the time of diabetes onset. Low non-fasting serum C-peptide (<0.6 nmol/L) between 3 and 10 years after diabetes diagnosis will be considered a biomarker for T1D as it reflects the loss of insulin secretion ability. Participating centres are enrolling youth (<19 years old) either with established diabetes (duration 3-10 years) for a cross-sectional evaluation or with recent onset diabetes (duration 3 weeks-15 months) for the longitudinal observation with annual visits for 3 years. Cross-sectional data will be used to develop models. Longitudinal data will be used to externally validate the best-fitting model.

RESULTS

The results are expected to improve the ability to classify diabetes type in a large and growing subset of children who have an unclear form of diabetes at diagnosis.

CONCLUSIONS

Accurate and timely classification of diabetes type will help establish the correct clinical management early in the course of the disease.

Simplification of Complex Insulin Regimens with IdegLira in People with Type 2 Diabetes: Literature Review and Clinical Recommendations

INTRODUCTION

This study developed a simple algorithm based on clinical results described in medical literature and which allows one to simplify complex insulin regimes with IdegLira to avoid adverse events related to the complexity of some insulin treatments.

METHODS

We conducted a systematic review of the literature that allowed us to identify studies that evaluated the clinical result of simplifying complex insulin regimes. The authors reviewed the common factors these simpler regimes had, including the type of patients who used them.

RESULTS

We found nine clinical studies published between 2017 and 2022, eight performed in Europe and one in Latin America. The monitoring time of the studies ranged between 3 and 18 months. The size of the study populations was between 61 and 611 patients (the latter was in five countries). In all studies, HbA1c decreased by 0.6-1.7% and the weight decreased by 0.1-3.11 kg.

CONCLUSIONS

On the basis of the findings of these studies, we made some recommendations for clinical practice to simplify treatment. The results of these studies support an algorithm that simplifies the treatment of complex insulin regimens.

Predictors of Responsiveness to GLP-1 Receptor Agonists in Insulin-Treated Patients with Type 2 Diabetes

Background

Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are potent antihyperglycemic agents with beneficial effects on weight, cardiovascular, and renal outcomes. Physicians lack guidance as to which patients with insulin-requiring type 2 diabetes will respond best to GLP-1 RAs with respect to glycemic control, insulin dose reduction, and weight loss. This study evaluated the efficacy of GLP-1 RAs in patients with type 2 diabetes on insulin and patient factors that may predict a beneficial clinical response.

Methods

Adults with type 2 diabetes treated with insulin who had a GLP-1 RA added to their regimen were evaluated retrospectively. Baseline parameters and outcomes at 3, 6, and 12 months were collected.

Results

Among the 81 patients included, there was a mean reduction in hemoglobin A1C of 0.94% (SD, 0.26; p = 0.0007), 0.40% (SD, 0.21; p = 0.0636), and 0.58% (SD, 0.23, p = 0.0154) at 3, 6, and 12 months, respectively, following the addition of a GLP-1 RA. There was also a reduction in body weight noted at each time point. Baseline characteristics including BMI, duration of diabetes, and insulin requirement did not significantly affect A1C reduction when GLP-1 RA was added. At 3 months, patients with a random C-peptide that was normal (≥0.8 ng/ml) were significantly more likely to have discontinued insulin than those with random C-peptide that was low (<0.8 ng/ml) (11 of 23 vs. 0 of 7 patients, p = 0.029).

Conclusions

The addition of a GLP-1 RA reduced HbA1C, weight, and insulin requirements in this cohort of patients with type 2 diabetes on insulin. BMI, baseline insulin dose, and diabetes duration did not predict response. A C-peptide level ≥ 0.8 ng/ml predicted a beneficial response after 3 months of therapy.

Prevalence and characteristics of misdiagnosed adult-onset type 1 diabetes mellitus in Thai people by random plasma C-peptide testing

Background

It is critical to determine the exact type of diabetes because misclassification led to inappropriate treatments. The classification of DM can be aided by the measurement of pancreatic autoantibodies and plasma C-peptide levels. Previous studies suggested that random plasma C-peptide testing in those with clinically diagnosed adult T1DM of at least 3 years duration has led to reclassification in some cases.

Aim

This study aimed to assess the prevalence and characteristics of misdiagnosed adult-onset type 1 diabetes mellitus in Thai people by random plasma C-peptide testing.

Methods

A cross-sectional study of adult Thai patients diagnosed with clinically diagnosed T1DM and DM duration of at least 3 years at Theptarin Hospital, a diabetes center in Bangkok, Thailand was studied. Clinically misdiagnosis of T1DM was defined by preserved endogenous insulin secretion. Characteristics of the misdiagnosed patients were compared with definite T1DM patients.

Results

A total of 73 patients (females 52.1%, mean age 42.2 ± 12.5 years, duration of DM 20.3 ± 11.3 years) were studied. The prevalence of available anti-GAD and anti-IA2 were 53.3% and 20.8%, respectively. Preserved endogenous insulin secretion evaluated by random C-peptide or stimulated C-peptide was found in 8 patients (11.0%). The misdiagnosed patients had higher prevalence of hypertension and diabetic complications. Three patients were suspected to have monogenic diabetes and five patients were reclassified as possible T2DM.

Conclusions

Approximately one-tenth of adult T1DM patients were misdiagnosed. Random plasma C-peptide testing at least 3 years after a diagnosis of T1DM was superior to the measurement of pancreatic autoantibodies. Our present study highlights the need to increase accuracy in the diagnosis of T1DM patients by re-assessing endogenous insulin production with measurement of random plasma C-peptide levels.

Admission eGFR predicts in-hospital mortality independently of admission glycemia and C-peptide in patients with type 2 diabetes mellitus and COVID-19

OBJECTIVE

Type 2 diabetes mellitus (T2DM) and impaired kidney function are associated with a higher risk of poor outcomes of COVID-19. We conducted a retrospective study in hospitalized T2DM patients with COVID-19 to assess the association between in-hospital mortality and admission values of different hematological/biochemical parameters, including estimated glomerular filtration rate (eGFR), plasma glucose and C-peptide (as a marker of beta-cell function).

METHODS

The study included T2DM patients with confirmed SARS-CoV-2 infection who were consecutively admitted to our Institution between October 1, 2020 and April 1, 2021.

RESULTS

Patients (n = 74) were categorized into survivors (n = 55) and non-survivors (n = 19). Non-survivors exhibited significantly higher median WBC count, D-dimer, neutrophil-to-lymphocyte ratio, hsCRP, and procalcitonin levels, as well as significantly lower median serum 25(OH)D levels compared to survivors. Non-survivors exhibited significantly higher median admission plasma glucose (APG) values compared to survivors (210 vs 166 mg/dL; p = 0.026). There was no statistically significant difference in median values of plasma C-peptide between non-survivors and survivors (3.55 vs 3.24 ng/mL; p = 0.906). A significantly higher percentage of patients with an eGFR < 60 mL/min/1.73 m² was observed in the non-survivor group as compared to the survivor group (57.9% vs 23.6%; p = 0.006). A multivariate analysis performed by a logistic regression model after adjusting for major confounders (age, sex, body mass index, major comorbidities) showed a significant inverse association between eGFR values and risk of in-hospital mortality (OR, 0.956; 95% CI, 0.931-0.983; p = 0.001). We also found a significant positive association between WBC count and risk of in-hospital mortality (OR, 1.210; 95% CI, 1.043-1.404; p = 0.011).

CONCLUSIONS

Admission eGFR and WBC count predict in-hospital COVID-19 mortality among T2DM patients, independently of traditional risk factors, APG and random plasma C-peptide. Hospitalized patients with COVID-19 and comorbid T2DM associated with impaired kidney function at admission should be considered at high risk for adverse outcomes and death.

Fasting and meal-stimulated serum C-peptide in long-standing type 1 diabetes mellitus

AIMS

This study aims to evaluate the stability of C-peptide over time and to compare fasting C-peptide and C-peptide response after mixed-meal tolerance test (MMTT) at T90 or T120 with C-peptide area under the curve (AUC) in long-standing type 1 diabetes.

METHODS

We included 607 type 1 diabetes individuals with diabetes duration >5 years. C-peptide concentrations (ultrasensitive assay) were collected in the fasting state, and in a subpopulation after MMTT (T0, just prior to, T30-T60-T90-T120, 30-120 min after ingestion of mixed-meal) (n = 168). Fasting C-peptide concentrations (in n = 535) at Year 0 and Year 1 were compared. The clinical determinants associated with residual C-peptide secretion and the correspondence of C-peptide at MMTT T90 / T120 and total AUC were assessed.

RESULTS

A total of 153 participants (25%) had detectable fasting serum C-peptide (i.e ≥ 3.8 pmol/L). Fasting C-peptide was significantly lower at Year 1 (p < 0.001, effect size = -0.16). Participants with higher fasting C-peptide had a higher age at diagnosis and shorter disease duration and were less frequently insulin pump users. Overall, 109 of 168 (65%) participants had both non-detectable fasting and post-meal serum C-peptide concentrations. The T90 and T120 C-peptide values at MMTT were concordant with total AUC. In 17 (10%) individuals, C-peptide was only detectable at MMTT and not in the fasting state.

CONCLUSIONS

Stimulated C-peptide was detectable in an additional 10% of individuals compared with fasting in individuals with >5 years of diabetes duration. T90 and T120 MMTT measurements showed good concordance with the MMTT total AUC. Overall, there was a decrease of C-peptide at 1-year follow-up.

Preserved C-peptide secretion is associated with higher time in range (TIR) on intermittently scanned continuous glucose monitoring in Chinese adults with type 1 diabetes

OBJECTIVE

To explore the relationship between C-peptide secretion and time in range (TIR) in adult patients with type 1 diabetes.

METHODS

From December 2018 to December 2020, 76 type 1 diabetes participants were enrolled from the Department of Endocrinology and Metabolism of Peking University People's Hospital. All participants wore intermittently scanned continuous glucose monitoring (isCGM), and insulin dosage was adjusted according to standardized clinical procedures. Subjects were divided into low C-peptide group (<10 pmol/L) and preserved C-peptide group (10-200 pmol/L) based on fasting serum C-peptide levels. Differences of TIR, metrics related to glucose variability and hypoglycemic events were compared.

RESULTS

A total of 94,846 isCGM values obtained from 39 male and 37 female participants were analyzed. Individuals with preserved C-peptide secretion had shorter diabetes duration (2.0 (0.5, 10.0) vs 10.0 (3.0, 18.3) years, P = 0.002). TIR was higher in the individuals with preserved C-peptide than those with decreased C-peptide (67.1% (54.2, 75.8) vs 45.5% (33.9, 56.1), P < 0.001), and time above range was significantly lower in those with preserved C-peptide (28.0% (15.6, 42.4) vs 49.4% (39.1, 64.2), P < 0.001). Preserved C-peptide was associated with lower glucose variability, as defined by s.d. (3.0 mmol/L (2.6, 3.4) vs 3.8 mmol/L (3.2, 4.3), P < 0.001) and interquartile range (4.3 mmol/L (3.1, 4.8) vs 5.3 mmol/L (4.5, 6.3), P < 0.001). Metrics related to hypoglycemia were not different between the two groups.

CONCLUSION

Preserved C-peptide secretion was associated with higher TIR and lower glucose variability in Chinese type 1 diabetes adults.

Prospective associations of hemoglobin A1c and c-peptide with risk of diabetes-related cancers in the Cancer Prevention Study-II Nutrition Cohort

Self-reported type 2 diabetes mellitus (T2DM) is a risk factor for many cancers, suggesting its pathology relates to carcinogenesis. We conducted a case-cohort study to examine associations of hemoglobin A1c (HbA1c) and c-peptide with cancers associated with self-reported T2DM. This study was drawn from a prospective cohort of 32,383 women and men who provided blood specimens at baseline: c-peptide and HbA1c were assessed in 3,000 randomly selected participants who were cancer-free-at-baseline and an additional 2,281 participants who were cancer-free-at-baseline and subsequently diagnosed with incident colorectal, liver, pancreatic, female breast, endometrial, ovarian, bladder, or kidney cancers. Weighted-Cox regression models estimated hazards ratios (HRs) and 95% confidence intervals (CI), adjusted for covariates. C-peptide was associated with higher risk of liver cancer (per standard deviation (SD) HR: 1.80; 95%CI: 1.32-2.46). HbA1c was associated with higher risk of pancreatic cancer (per SD HR: 1.21 95%CI 1.05-1.40) and with some suggestion of higher risks for all-cancers-of-interest (per SD HR: 1.05; 95%CI: 0.99-1.11) and colorectal (per SD HR: 1.09; 95%CI: 0.98-1.20), ovarian (per SD HR: 1.18; 95%CI 0.96-1.45) and bladder (per SD HR: 1.08; 95%CI 0.96-1.21) cancers. Compared to no self-reported T2DM and HbA1c <6.5% (reference group), self-reported T2DM and HbA1c <6.5% (i.e., T2DM in good glycemic control) was not associated with risk of colorectal cancer, whereas it was associated with higher risks of all-cancers-of-interest combined (HR: 1.28; 95%CI: 1.01-1.62), especially for breast and endometrial cancers. Additional large, prospective studies are needed to further explore the roles of hyperglycemia, hyperinsulinemia, and related metabolic traits with T2DM-associated cancers to better understand the mechanisms underlying the self-reported T2DM-cancer association and to identify persons at higher cancer risk.

Diagnostic Test Accuracy of Urine C-peptide Creatinine Ratio for the Correct Identification of the Type of Diabetes: A Systematic Review

Objective: To examine the accuracy of urine c-peptide creatinine ratio (UCPCR) for identifying the type of diabetes in appropriate clinical settings. Design: Systematic review of test accuracy studies on patients with different forms of diabetes. Data sources: Medline, Embase and Cochrane library databases from 1 January 2000 to 15 November 2020. Eligibility criteria: Studies reporting the use of UCPCR for diagnosing patients with type 1 diabetes mellitus (T1DM), type 2 diabetes mellitus (T2DM) and monogenic forms of diabetes (categorized as maturity-onset diabetes of the young [MODY]). Study selection and data synthesis: Two reviewers independently assessed articles for inclusion and assessed the methodological quality of the studies using the Quality Assessment of Diagnostic Accuracy Studies-2 tool, with input from a third reviewer to reach consensus when there was a dispute. Meta-analysis was performed with the studies reporting complete data to derive the pooled sensitivity, specificity and diagnostic odds ratio (DOR), and narrative synthesis only for those with incomplete data. Results: Nine studies with 4,488 patients were included in the qualitative synthesis, while only four of these (915 patients) had complete data and were included in the quantitative synthesis. All the studies had moderate risk of bias and applicability concerns. Meta-analysis of three studies (n=130) revealed sensitivity, specificity and DOR of 84.4% (95% confidence interval [CI] 68.1-93.2%), 91.6% (82.8-96.1%) and 59.9 (32.8-106.0), respectively, for diagnosing T1DM using a UCPCR cut-off of <0.2 nmol/mmol. For participants with T2DM (three studies; n=739), UCPCR >0.2 nmol/mmol was associated with sensitivity, specificity and DOR of 92.8% (84.2-96.9%), 81.6% (61.3-92.5%) and 56.9 (31.3-103.5), respectively. For patients with MODY in the appropriate clinical setting, a UCPCR cut-off of >0.2 nmol/mmol showed sensitivity, specificity and DOR of 85.2% (73.1-92.4%), 98.0% (92.4-99.5%) and 281.8 (57.5-1,379.7), respectively. Conclusions: Based on studies with moderate risk of bias and applicability concerns, UCPCR confers moderate to high sensitivity, specificity, and DOR for correctly identifying T1DM, T2DM and monogenic diabetes in appropriate clinical settings. Large multinational studies with multi-ethnic participation among different age groups are necessary before this test can be routinely used in clinical practice. Study registration: Protocol was registered as PROSPERO CRD42017060633.

Capturing the real-world benefit of residual β-cell function during clinically important time-periods in established Type 1 diabetes

AIMS

Many individuals with type 1 diabetes retain residual β-cell function, with increased endogenous insulin secretion associated with reduced hyperglycaemia, hypoglycaemia and glycaemic variability. However, it is unknown when these improvements occur during the day. Dysglycaemia is common in overnight and postprandial periods and associated with diabetes complications. Therefore, this study aimed to determine the influence of residual β-cell function upon nocturnal and postprandial glycaemic control in established type 1 diabetes.

METHODS

Under free-living conditions, 66 participants wore a blinded continuous glucose monitor (CGM), kept a food diary, and completed a stimulated urine C-peptide creatinine (UCPCR) test. Nocturnal, and postprandial CGM outcomes (participant means and discrete event analysis) were compared between UCPCR groups: undetectable (Cpep_und ), low (Cpep_low : 0.001-0.19 nmol/mmol) and high (Cpep_high : ≥0.2 nmol/mmol).

RESULTS

Greater β-cell function was associated with incremental improvements in glycaemia. Cpep_high spent significantly greater time in normoglycaemia than Cpep_und overnight (76 ± 20% vs. 58 ± 20%, p = 0.005) and 0-300 mins postprandially (68 ± 22% vs. 51 ± 22%, p = 0.045), while also having reducing nocturnal variability (SD 1.12 ± 0.41 vs. 1.52 ± 0.43 mmol/L, p = 0.010). Analysis of individual events, controlling for diabetes duration, BMI, basal insulin, use of a continuous or flash glucose monitor and (for postprandial) meal type, carbohydrate and bolus insulin intake, replicated the group findings, additionally demonstrating Cpep_und had increased hyperglycaemia versus Cpep_low overnight and increased postprandial hypoglycaemic events compared with Cpep_high . For all participants, breakfast had a significantly higher incremental area under the curve than lunch and dinner.

CONCLUSIONS

Residual β-cell function is associated with improved nocturnal and postprandial glycaemic control. These data may be of clinical importance for identifying specific periods and individuals where further glycaemic management strategies would be beneficial.

Stimulated UCPCR Levels Are Lower in People With Type 1 Diabetes Than in Other Diabetes Types in Sub-Saharan Africa: Results From a Preliminary Cross-Sectional Study

Background

The clinical utility of Urinary C-Peptide to Creatinine Ratio (UCPCR) is well understood in people with different types of diabetes in Caucasian populations, but studies are lacking in African populations. We, therefore, aimed to examine Urinary C-Peptide to Creatinine Ratio levels among groups of people with different types of diabetes in a sub-Saharan African population.

Methods

A total of 47 adults with diabetes; 10 with type 1 diabetes, 26 with type 2 diabetes, 11 with ketosis-prone diabetes, and 22 healthy control individuals, were recruited from Yaoundé Central Hospital in Cameroon. Fasting blood glucose and C-peptide were measured in venous blood and urine. Stimulated Urinary C-Peptide to Creatinine Ratio was determined in all subjects after ingestion of a standardized mixed meal. We compared the stimulated Urinary C-peptide to Creatinine Ration concentration in subjects with type 1 diabetes to the other groups.

Results

The basal C-peptide and HOMA-β were lower in T1D than in the T2D group [median 57 (34, 69) vs. 398 (335, 502) pmol/l; p ≤ 0.001] and [median 3.0 (1.63, 5.25) vs. 30.6 (17.94, 45.03); p < 0.001] respectively. Also, basal C-peptide and HOMA-β were lower in T1D than in those with KPD [median 57 (34, 69) vs. 330 (265, 478) pmol/l; p = 0.003] and [median 3.0 (1.63, 5.25) vs. 47.1 (16.2, 63.1), p = 0.001] respectively. Basal C-peptide was not different between participants with T2D and KPD; 398 (335, 502) vs. 330 (265, 478) pmol/l, p = 0.19. Stimulated UCPCR was lower in T1D compared to T2D, KPD and control participants; [median 0.29 (0.14, 0.68) vs. 0.89 (0.40, 1.69) nmol/moll; p = 0.009], [median 0.29 (0.14, 0.68) vs. 1.33 (0.84, 1.59) nmol/mol; p = 0.006] and [median 0.29 (0.14, 0.68) vs. 1.21 (0.85, 1.21) nmol/mol; p = 0.005] respectively. However, stimulated UCPCR was similar between the T2D and KPD study participants; 0.89 (0.40, 1.69) vs. 1.33 (0.84, 1.59) nmol/mol, p = 0.36.

Conclusions

Stimulated Urinary C-Peptide to Creatinine Ratio (UCPCR) is lower in participants with type 1 diabetes compared to those with other types of diabetes in this population. This means stimulated UCPCR could potentially differentiate type 1 diabetes from other diabetes types among people with diabetes in sub-Saharan Africa.

Biomarkers of glucose homeostasis and inflammation with risk of prostate cancer: A case-cohort study

BACKGROUND

Few prospective studies have examined biomarkers of glucose homeostasis or inflammation with prostate cancer risk by tumor stage or grade.

METHODS

We conducted a case-cohort study to examine associations of pre-diagnosis hemoglobin A1c (HbA1c), c-peptide, and c-reactive protein (CRP) with prostate cancer risk overall and stratified by tumor stage and grade. The study included 390 non-aggressive (T1-2, N0, M0 and Gleason score <8) and 313 aggressive cases (T3-4, or N1, or M1, or Gleason score 8-10) diagnosed after blood draw (1998-2001) and up to 2013, and a random sub-cohort of 1,303 cancer-free men at blood draw in the Cancer Prevention Study-II Nutrition Cohort. Prentice-weighted Cox proportional hazards regression models were used to estimate hazards ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

In the multivariable-adjusted model without body mass index (BMI), HbA1c was inversely associated with non-aggressive prostate cancer (HR per unit increase: 0.89, 95% CI: 0.80-1.00, P=0.04). Analyses stratified by tumor stage and grade separately showed that HbA1c was inversely associated with low-grade prostate cancer (HR per unit increase: 0.89, 95% CI: 0.80-1.00) and positively associated with high-grade prostate cancer (HR per unit increase: 1.15, 95% CI: 1.01-1.30). C-peptide and CRP were not associated with prostate cancer overall or by stage or grade.

CONCLUSIONS

The present study suggests that associations of hyperglycemia with prostate cancer may differ by tumor grade and stage.

IMPACT

Future studies need to examine prostate cancer by tumor stage and grade, and to better understand the role of hyperglycemia in prostate cancer progression.

Urinary metabolic biomarkers of diet quality in European children are associated with metabolic health

Urinary metabolic profiling is a promising powerful tool to reflect dietary intake and can help understand metabolic alterations in response to diet quality. Here, we used 1H NMR spectroscopy in a multicountry study in European children (1147 children from 6 different cohorts) and identified a common panel of 4 urinary metabolites (hippurate, N-methylnicotinic acid, urea, and sucrose) that was predictive of Mediterranean diet adherence (KIDMED) and ultra-processed food consumption and also had higher capacity in discriminating children's diet quality than that of established sociodemographic determinants. Further, we showed that the identified metabolite panel also reflected the associations of these diet quality indicators with C-peptide, a stable and accurate marker of insulin resistance and future risk of metabolic disease. This methodology enables objective assessment of dietary patterns in European child populations, complementary to traditional questionary methods, and can be used in future studies to evaluate diet quality. Moreover, this knowledge can provide mechanistic evidence of common biological pathways that characterize healthy and unhealthy dietary patterns, and diet-related molecular alterations that could associate to metabolic disease.

Type 2 diabetes in prepubertal children

OBJECTIVE

Puberty-induced insulin resistance is considered critical in the pathogenesis of type 2 diabetes (T2D) in youth. The development of T2D before puberty suggests distinct risk factors and pathophysiology but, because of its rarity, this has not been well studied. We aimed to describe the clinical characteristics of children with T2D diagnosed before the onset of puberty.

RESEARCH DESIGN AND METHODS

We retrospectively studied all children with autoantibody-negative T2D and available pubertal development assessment seen at our center between July 2016 and July 2019, and compared characteristics of those at Tanner stage I (prepubertal, n = 35) versus those at Tanner II-V of pubertal development (n = 341).

RESULTS

At T2D diagnosis, prepubertal children compared with those at Tanner II-V had higher body mass index z-score (p = 0.003) and higher C-peptide (p = 0.003) (while glucose levels were not significantly different), with differences retaining significance after adjustment for glucose, race/ethnicity and sex. Dyslipidemia occurred in 100% of prepubertal children versus 89.7% of those diagnosed later (p = 0.036). Of the prepubertal children diagnosed under age 10 (n = 13), 69.2% were female, 100% racial/ethnic minority, 100% had obesity with history of dyslipidemia and none with diabetic ketoacidosis.

CONCLUSIONS

T2D, although rarely, can develop before puberty. Children with T2D diagnosed in the prepubertal period have more severe obesity, greater insulin resistance, and more frequent dyslipidemia than older youth. These findings suggest that children with prepubertal T2D are at increased risk for associated morbidity compared with older youth and underscore the significance of interventions to prevent and treat obesity in early childhood.

Adult-Onset Type 1 Diabetes: Current Understanding and Challenges

Recent epidemiological data have shown that more than half of all new cases of type 1 diabetes occur in adults. Key genetic, immune, and metabolic differences exist between adult- and childhood-onset type 1 diabetes, many of which are not well understood. A substantial risk of misclassification of diabetes type can result. Notably, some adults with type 1 diabetes may not require insulin at diagnosis, their clinical disease can masquerade as type 2 diabetes, and the consequent misclassification may result in inappropriate treatment. In response to this important issue, JDRF convened a workshop of international experts in November 2019. Here, we summarize the current understanding and unanswered questions in the field based on those discussions, highlighting epidemiology and immunogenetic and metabolic characteristics of adult-onset type 1 diabetes as well as disease-associated comorbidities and psychosocial challenges. In adult-onset, as compared with childhood-onset, type 1 diabetes, HLA-associated risk is lower, with more protective genotypes and lower genetic risk scores; multiple diabetes-associated autoantibodies are decreased, though GADA remains dominant. Before diagnosis, those with autoantibodies progress more slowly, and at diagnosis, serum C-peptide is higher in adults than children, with ketoacidosis being less frequent. Tools to distinguish types of diabetes are discussed, including body phenotype, clinical course, family history, autoantibodies, comorbidities, and C-peptide. By providing this perspective, we aim to improve the management of adults presenting with type 1 diabetes.

Betulinic acid reduces the complications of autoimmune diabetes on the body and kidney through effecting on inflammatory cytokines in C57BL/6 mice

Autoimmune diabetes is one of the most common metabolic diseases with increasing prevalence in the past decades in which pancreatic Langerhans β cells are destroyed and lead to lack of insulin due to increased blood sugar. One of the consequences of diabetes is glomerular disease of the kidney, also called diabetes nephropathy. Different studies have been carried out on the effects of triterpenoids and their medicinal effects on diabetes mellitus. betulinic acid, a pentacyclic triterpenoid of Terpenes, is found in bushes and trees. Its medical effects are also approved by many studies. In this survey, we studied the effect of betulinic acid on diabetic inbred C57BL/6 male mice. They were randomly divided to three groups. Group A: Consisted of healthy mice which received citrate buffer. Group B: Diabetic mice without any treatment and group C: Treated diabetic mice with betulinic acid. The level of blood insulin level, fasting blood glucose, C-peptide, TNF-α, IFN-γ, and IL-1 cytokines were measured and pathologic studies of the kidney were performed. The results showed that betulinic acid could increase insulin and C-peptide, and decrease fasting blood sugar, kidney lesions and TNF-α, IFN-γ, IL-1 in the treated groups. The differences were significant except for IL-1. Betulinic acid through reduction of inflammatory cytokines could have positive effects on inflammatory and autoimmune disease including autoimmune diabetes.

Genetic Composition and Autoantibody Titers Model the Probability of Detecting C-Peptide Following Type 1 Diabetes Diagnosis

We and others previously demonstrated that a type 1 diabetes genetic risk score (GRS) improves the ability to predict disease progression and onset in at-risk subjects with islet autoantibodies. Here, we hypothesized that GRS and islet autoantibodies, combined with age at onset and disease duration, could serve as markers of residual β-cell function following type 1 diabetes diagnosis. Generalized estimating equations were used to investigate whether GRS along with insulinoma-associated protein-2 autoantibody (IA-2A), zinc transporter 8 autoantibody (ZnT8A), and GAD autoantibody (GADA) titers were predictive of C-peptide detection in a largely cross-sectional cohort of 401 subjects with type 1 diabetes (median duration 4.5 years [range 0-60]). Indeed, a combined model with incorporation of disease duration, age at onset, GRS, and titers of IA-2A, ZnT8A, and GADA provided superior capacity to predict C-peptide detection (quasi-likelihood information criterion [QIC] = 334.6) compared with the capacity of disease duration, age at onset, and GRS as the sole parameters (QIC = 359.2). These findings support the need for longitudinal validation of our combinatorial model. The ability to project the rate and extent of decline in residual C-peptide production for individuals with type 1 diabetes could critically inform enrollment and benchmarking for clinical trials where investigators are seeking to preserve or restore endogenous β-cell function.

Clinical Impact of Residual C-Peptide Secretion in Type 1 Diabetes on Glycemia and Microvascular Complications

OBJECTIVE

To quantify the relationship of residual C-peptide secretion to glycemic outcomes and microvascular complications in type 1 diabetes.

RESEARCH DESIGN AND METHODS

C-peptide was measured in an untimed blood sample in the Scottish Diabetes Research Network Type 1 Bioresource (SDRNT1BIO) cohort of 6,076 people with type 1 diabetes monitored for an average of 5.2 years.

RESULTS

In regression models adjusted for age at onset and duration, effect sizes for C-peptide ≥200 vs. <5 pmol/L were as follows: insulin dose at baseline, 27% lower (P = 2 × 10^-39); HbA_1c during follow-up, 4.9 mmol/mol lower (P = 3 × 10^-13); hazard ratio for hospital admission for diabetic ketoacidosis during follow-up, 0.44 (P = 0.0001); odds ratio for incident retinopathy, 0.51 (P = 0.0003). Effects on the risk of serious hypoglycemic episodes were detectable at lower levels of C-peptide, and the form of the relationship was continuous down to the limit of detection (3 pmol/L). In regression models contrasting C-peptide 30 to <200 pmol/L with <5 pmol/L, the odds ratio for self-report of at least one serious hypoglycemic episode in the last year was 0.56 (P = 6 × 10^-8), and the hazard ratio for hospital admission for hypoglycemia during follow-up was 0.52 (P = 0.03).

CONCLUSIONS

These results in a large representative cohort suggest that even minimal residual C-peptide secretion could have clinical benefit in type 1 diabetes, in contrast to a follow-up study of the Diabetes Control and Complications Trial (DCCT) intensively treated cohort where an effect on hypoglycemia was seen only at C-peptide levels ≥130 pmol/L. This has obvious implications for the design and evaluation of trials of interventions to preserve or restore pancreatic islet function in type 1 diabetes.

Approach to the Patient with MODY-Monogenic Diabetes

Maturity-onset diabetes of the young, or MODY-monogenic diabetes, is a not-so-rare collection of inherited disorders of non-autoimmune diabetes mellitus that remains insufficiently diagnosed despite increasing awareness. These cases are important to efficiently and accurately diagnose, given the clinical implications of syndromic features, cost-effective treatment regimen, and the potential impact on multiple family members. Proper recognition of the clinical manifestations, family history, and cost-effective lab and genetic testing provide the diagnosis. All patients must undergo a thorough history, physical examination, multigenerational family history, lab evaluation (glycated hemoglobin A1c [HbA1c], glutamic acid decarboxylase antibodies [GADA], islet antigen 2 antibodies [IA-2A], and zinc transporter 8 [ZnT8] antibodies). The presence of clinical features with 3 (or more) negative antibodies may be indicative of MODY-monogenic diabetes, and is followed by genetic testing. Molecular genetic testing should be performed before attempting specific treatments in most cases. Additional testing that is helpful in determining the risk of MODY-monogenic diabetes is the MODY clinical risk calculator (>25% post-test probability in patients not treated with insulin within 6 months of diagnosis should trigger genetic testing) and 2-hour postprandial (after largest meal of day) urinary C-peptide to creatinine ratio (with a ≥0.2 nmol/mmol to distinguish HNF1A- or 4A-MODY from type 1 diabetes). Treatment, as well as monitoring for microvascular and macrovascular complications, is determined by the specific variant that is identified. In addition to the diagnostic approach, this article will highlight recent therapeutic advancements when patients no longer respond to first-line therapy (historically sulfonylurea treatment in many variants).

LEARNING OBJECTIVES

Upon completion of this educational activity, participants should be able to.

TARGET AUDIENCE

This continuing medical education activity should be of substantial interest to endocrinologists and all health care professionals who care for people with diabetes mellitus.

Fasting parameters for estimation of stimulated β cell function in islet transplant recipients with or without basal insulin treatment

In order to assess β cell secretory capacity after islet transplantation, standardized mixed meal stimulation tests are often used. But these tests are cumbersome and the effect of exogenous insulin on the test results is unclear. The aim of our study was to determine to what extent fasting glycemic indices can estimate stimulated β cell function in islet transplant recipients with and without basal insulin. In total 100 mixed meal stimulation tests, including 31 with concurrent basal insulin treatment, were performed in 36 islet transplant recipients. In a multivariate model, fasting C-peptide and fasting glucose together estimated peak C-peptide with R²  = .87 and area under the curve (AUC) C-peptide with a R²  = .93. There was a larger increase of glucose during tests in which exogenous insulin was used (+7.9 vs +5.3 mmol/L, P < .001) and exogenous insulin use was associated with a slightly lower estimated peak C-peptide (relative change: -15%, P = .02). In islet transplant recipients the combination of fasting C-peptide and glucose can be used to accurately estimate stimulated β cell function after a mixed meal stimulation test, whether exogenous basal insulin is present or not. These data indicate that graft function can be reliably determined during exogenous insulin treatment and that regular islet graft stimulation tests can be minimized.

Postexercise Glycemic Control in Type 1 Diabetes Is Associated With Residual β-Cell Function

OBJECTIVE

To investigate the impact of residual β-cell function on continuous glucose monitoring (CGM) outcomes following acute exercise in people with type 1 diabetes (T1D).

RESEARCH DESIGN AND METHODS

Thirty participants with T1D for ≥3 years were recruited. First, participants wore a blinded CGM unit for 7 days of free-living data capture. Second, a 3-h mixed-meal test assessed stimulated C-peptide and glucagon. Peak C-peptide was used to allocate participants into undetectable (Cpep_und <3 pmol/L), low (Cpep_low 3-200 pmol/L), or high (Cpep_high >200 pmol/L) C-peptide groups. Finally, participants completed 45 min of incline treadmill walking at 60% VO_2peak followed by a further 48-h CGM capture.

RESULTS

CGM parameters were comparable across groups during the free-living observation week. In the 12- and 24-h postexercise periods (12 h and 24 h), the Cpep_high group had a significantly greater amount of time spent with glucose 3.9-10 mmol/L (12 h, 73.5 ± 27.6%; 24 h, 76.3 ± 19.2%) compared with Cpep_low (12 h, 43.6 ± 26.1%, P = 0.027; 24 h, 52.3 ± 25.0%, P = 0.067) or Cpep_und (12 h, 40.6 ± 17.0%, P = 0.010; 24 h, 51.3 ± 22.3%, P = 0.041). Time spent in hyperglycemia (12 h and 24 h glucose >10 and >13.9 mmol/L, P < 0.05) and glycemic variability (12 h and 24 h SD, P < 0.01) were significantly lower in the Cpep_high group compared with Cpep_und and Cpep_low. Change in CGM outcomes from pre-exercise to 24-h postexercise was divergent: Cpep_und and Cpep_low experienced worsening (glucose 3.9-10 mmol/L: -9.1% and -16.2%, respectively), with Cpep_high experiencing improvement (+12.1%) (P = 0.017).

CONCLUSIONS

Residual β-cell function may partially explain the interindividual variation in the acute glycemic benefits of exercise in individuals with T1D. Quantifying C-peptide could aid in providing personalized and targeted support for exercising patients.

Management of Latent Autoimmune Diabetes in Adults: A Consensus Statement From an International Expert Panel

A substantial proportion of patients with adult-onset diabetes share features of both type 1 diabetes (T1D) and type 2 diabetes (T2D). These individuals, at diagnosis, clinically resemble T2D patients by not requiring insulin treatment, yet they have immunogenetic markers associated with T1D. Such a slowly evolving form of autoimmune diabetes, described as latent autoimmune diabetes of adults (LADA), accounts for 2-12% of all patients with adult-onset diabetes, though they show considerable variability according to their demographics and mode of ascertainment. While therapeutic strategies aim for metabolic control and preservation of residual insulin secretory capacity, endotype heterogeneity within LADA implies a personalized approach to treatment. Faced with a paucity of large-scale clinical trials in LADA, an expert panel reviewed data and delineated one therapeutic approach. Building on the 2020 American Diabetes Association (ADA)/European Association for the Study of Diabetes (EASD) consensus for T2D and heterogeneity within autoimmune diabetes, we propose "deviations" for LADA from those guidelines. Within LADA, C-peptide values, proxy for β-cell function, drive therapeutic decisions. Three broad categories of random C-peptide levels were introduced by the panel: 1) C-peptide levels <0.3 nmol/L: a multiple-insulin regimen recommended as for T1D; 2) C-peptide values ≥0.3 and ≤0.7 nmol/L: defined by the panel as a "gray area" in which a modified ADA/EASD algorithm for T2D is recommended; consider insulin in combination with other therapies to modulate β-cell failure and limit diabetic complications; 3) C-peptide values >0.7 nmol/L: suggests a modified ADA/EASD algorithm as for T2D but allowing for the potentially progressive nature of LADA by monitoring C-peptide to adjust treatment. The panel concluded by advising general screening for LADA in newly diagnosed non-insulin-requiring diabetes and, importantly, that large randomized clinical trials are warranted.

Confirmation and Identification of Biomarkers Implicating Environmental Triggers in the Pathogenesis of Type 1 Diabetes

Multiple environmental triggers have been proposed to explain the increased incidence of type 1 diabetes (T1D). These include viral infections, microbiome disturbances, metabolic disorders, and vitamin D deficiency. Here, we used ELISA to examine blood plasma from juvenile T1D subjects and age-matched controls for the abundance of several circulating factors relevant to these hypotheses. We screened plasma for sCD14, mannose binding lectin (MBL), lipopolysaccharide binding protein (LBP), c-reactive protein (CRP), fatty acid binding protein 2 (FABP2), human growth hormone, leptin, total adiponectin, high molecular weight (HMW) adiponectin, total IgG, total IgA, total IgM, endotoxin core antibodies (EndoCAbs), 25(OH) vitamin D, vitamin D binding protein, IL-7, IL-10, IFN-γ, TNF-α, IL-17A, IL-18, and IL-18BPa. Subjects also were tested for prevalence of antibodies targeting adenovirus, parainfluenza 1/2/3, Coxsackievirus, cytomegalovirus, Epstein-Barr virus viral capsid antigen (EBV VCA), herpes simplex virus 1, and Saccharomyces cerevisiae. Finally, all subjects were screened for presence and abundance of autoantibodies targeting islet cell cytoplasmic proteins (ICA), glutamate decarboxylase 2 (GAD65), zinc transporter 8 (ZNT8), insulinoma antigen 2 (IA-2), tissue transglutaminase, and thyroid peroxidase, while β cell function was gauged by measuring c-peptide levels. We observed few differences between control and T1D subjects. Of these, we found elevated sCD14, IL-18BPa, and FABP2, and reduced total IgM. Female T1D subjects were notably elevated in CRP levels compared to control, while males were similar. T1D subjects also had significantly lower prevalence of EBV VCA antibodies compared to control. Lastly, we observed that c-peptide levels were significantly correlated with leptin levels among controls, but this relationship was not significant among T1D subjects. Alternatively, adiponectin levels were significantly correlated with c-peptide levels among T1D subjects, while controls showed no relationship between these two factors. Among T1D subjects, the highest c-peptide levels were associated with the lowest adiponectin levels, an indication of insulin resistance. In total, from our examination we found limited data that strongly support any of the hypotheses investigated. Rather, we observed an indication of unexplained monocyte/macrophage activation in T1D subjects judging from elevated levels of sCD14 and IL-18BPa. These observations were partnered with unique associations between adipokines and c-peptide levels among T1D subjects.

Ten-year remission rates in insulin-treated type 2 diabetes after biliopancreatic diversion with duodenal switch

BACKGROUND

Biliopancreatic diversion with duodenal switch (BPD-DS) confers the highest rate of type 2 diabetes (T2D) remission compared with other bariatric procedures. Previous studies suggest that type of antidiabetic therapy used before surgery and duration of disease influence postsurgical glycemic outcomes. Short-term, progressive improvement in insulin sensitivity and beta-cell function after metabolic surgery in patients with noninsulin-treated T2D has been demonstrated. Whether patients with more advanced disease can achieve sustained remission remains unclear.

OBJECTIVE

The aim of this study was to assess long-term glycemic outcomes in insulin-treated patients with T2D after BPD-DS and identify predictors of sustained diabetes remission or relapse.

SETTING

University-affiliated tertiary care center.

METHODS

Data from 141 patients with insulin-treated T2D who underwent BPD-DS between 1994 and 2006 with 10 years of follow-up data were collected from a prospective electronic database.

RESULTS

Follow-up was available in 132 patients (91%). At 10 years after metabolic surgery, 90 patients (68.1%) had a complete remission of diabetes, 3 (2.3%) had a partial remission, 21 (15.9%) had an improvement, and 3 (2.3%) were unchanged in their diabetes status. Fourteen patients died during the 10-year follow-up period. Relapse after an initial period of remission occurred in 15 (11.4%) patients. Insulin discontinuation was achieved in 97%. Duration of diabetes was an independent predictor of nonremission at 10 years.

CONCLUSIONS

The BPD-DS maintains remission at 10 years postoperatively in patients with more advanced diabetes. Long-term benefits of the BPD-DS on weight loss and glycemic control should be considered when offering metabolic surgery to patients with insulin-treated T2D.

Urinary C-peptide creatinine ratio to differentiate type 2 diabetes mellitus from type 1 in pediatric patients

Type 2 diabetes mellitus (T2DM) is frequently misdiagnosed in children and treated as type 1 DM (T1DM) with insulin. Urinary C-peptide to creatinine ratio (UCPCR) can be used to measure ß cell function and endogenous insulin. We aimed to assess the value of UCPCR to differentiate T2DM from T1DM in pediatric patients. We assessed UCPCR from urine sample taken 2 h after lunch in 50 children with T1DM and 30 children with T2DM (duration of the disease ≥ 2 years and without renal impairment). Fasting and postprandial C-peptide levels were also evaluated in all included children. Receiver operating characteristic (ROC) curve was performed to assess the optimal UCPCR cutoff level to differentiate T2DM from T1DM in children. UCPCR was significantly lower in children with T1DM compared with those with T2DM (P < 0.001). There was a significant positive correlation between UCPCR and fasting C-peptide, postprandial C-peptide, and age of onset. There was a significant negative correlation between the UCPCR and both HbA1c and duration of DM in T1DM. Fasting C-peptide had a sensitivity of 63%, a specificity of 84% at a cutoff point ≥ 1.3 ng/ml to differentiate T2DM from T1DM. Postprandial C-peptide had a sensitivity of 87%, a specificity of 86% at a cutoff point ≥ 3.2 ng/ml to differentiate T2DM from T1DM. Finally, UCPCR had a sensitivity of 97%, a specificity of 88% at a cutoff point ≥ 0.28 nmol/nmol to differentiate T2DM from T1DM in pediatric patients.Conclusion: UCPCR is an easy noninvasive reliable marker to differentiate T2DM from T1DM in pediatric patients.What is Known:• Type 2 DM (T2DM) is frequently misdiagnosed in children and treated as type 1 DM (T1DM) with insulin.• Urinary C-peptide to creatinine ratio (UCPCR) can be used to measure ß cell function and endogenous insulin.What is New:• We revealed that UCPCR had a sensitivity of 97%, a specificity of 88% at a cutoff point ≥ 0.28 nmol/nmol to differentiate T2DM from T1DM.• UCPCR is an easy noninvasive dependable marker to diagnose T2DM from T1DM in pediatric patients.

Glycemic variability indices determined by self-monitoring of blood glucose are associated with β-cell function in Chinese patients with type 2 diabetes

INTRODUCTION

Glycemic control plays an important role in diabetes management, and self-monitoring of blood glucose (SMBG) is critical to achieving good glycemic control. However, there are few studies about the relationship between SMBG-estimated glycemic indices and β-cell function. Here we investigated the association between glucose variation indices estimated by SMBG and β-cell function among Chinese patients with type 2 diabetes mellitus (T2DM).

METHODS

In this cross‑sectional study, 397 patients with T2DM were recruited from February 2015 to October 2016. β-cell function was monitored using the Homeostasis Model Assessment 2 (HOMA2)-%β index. The parameters evaluated by SMBG were the mean blood glucose (MBG), standard deviation of MBG (SDBG), largest amplitude of glycemic excursions (LAGE), and postprandial glucose excursion (PPGE).

RESULTS

HOMA2-%β was negatively correlated with SDBG, LAGE, PPGE, and MBG (r = -0.350, -0.346, -0.178, and -0.631, respectively; all p < 0.01). After adjusting for confounding characteristics (diabetic duration, triglyceride, total cholesterol, fasting C-peptide, HOMA2-insulin resistance index, hypoglycemia, and diabetic treatments) and glycated hemoglobin A1c on a continuous scale, odds ratios of SDBG, LAGE, PPGE, and MBG between the patients in the lowest and highest HOMA2-%β quartiles were 2.02 (1.14-3.57), 1.24 (1.04-1.49), 1.13 (0.86-1.51), and 2.26 (1.70-3.00). HOMA2-%β was independently associated with SDBG, LAGE, and MBG.

CONCLUSIONS

Increased SDBG and LAGE assessed by SMBG are associated with β-cell dysfunction in Chinese patients with T2DM.

Preserved C-peptide secretion is associated with fewer low-glucose events and lower glucose variability on flash glucose monitoring in adults with type 1 diabetes

AIMS/HYPOTHESIS

We aimed to assess whether persistence of C-peptide secretion is associated with less glucose variability and fewer low-glucose events in adults with type 1 diabetes who use flash monitoring.

METHODS

We performed a cross-sectional study of 290 adults attending a university teaching hospital diabetes clinic, with type 1 diabetes, who use flash monitoring and in whom a random plasma C-peptide was available in the past 2 years. Variables relating to flash monitoring were compared between individuals with low C-peptide (<10 pmol/l) and those with persistent C-peptide (either 10-200 pmol/l or 10-50 pmol/l). In addition, the relationship between self-reported hypoglycaemia and C-peptide was assessed (n = 167). Data are median (interquartile range).

RESULTS

Individuals with preserved C-peptide secretion (10-200 pmol/l) had shorter duration of diabetes (15 [9-24] vs 25 [15-34] years, p < 0.001) and older age at diagnosis (23 [14-28] vs 15 [9-25] years, p < 0.001), although current age did not differ in this cohort. Preserved C-peptide was associated with lower time with glucose <3.9 mmol/l (3% [2-6%] vs 5% [3-9%], p < 0.001), fewer low-glucose events per 2 week period (7 [4-10] vs 10 [5-16], p < 0.001), lower SD of glucose (3.8 [3.4-4.2] vs 4.1 [3.5-4.7] mmol/l, p = 0.017) and lower CV of glucose (38.0 [35.0-41.6] vs 41.8 [36.5-45.8], p < 0.001). These differences were also present in those with C-peptide 10-50 pmol/l and associations were independent of diabetes duration and estimated HbA_1c in logistic regression analysis. Preserved C-peptide was also associated with lower rates of self-reported asymptomatic hypoglycaemia (8.0% vs 22.8% in the past month, p = 0.028).

CONCLUSIONS/INTERPRETATION

Preserved C-peptide secretion is associated with fewer low-glucose events and lower glucose variability on flash monitoring. This suggests that individuals with preserved C-peptide may more safely achieve intensive glycaemic targets.

Prospective Association of Energy Balance Scores Based on Metabolic Biomarkers with Colorectal Cancer Risk

BACKGROUND

Energy balance-related factors, such as body mass index (BMI), diet, and physical activity, may influence colorectal cancer etiology through interconnected metabolic pathways, but their combined influence is less clear.

METHODS

We used reduced rank regression to derive three energy balance scores that associate lifestyle factors with combinations of prediagnostic, circulating levels of high-sensitivity C-reactive protein (hsCRP), C-peptide, and hemoglobin A_1c (HbA_1c) among 2,498 participants in the Cancer Prevention Study-II Nutrition Cohort. Among 114,989 participants, we verified 2,228 colorectal cancer cases. We assessed associations of each score with colorectal cancer incidence and by tumor molecular phenotypes using Cox proportional hazards regression.

RESULTS

The derived scores comprised BMI, physical activity, screen time, and 14 food groups, and explained 5.1% to 10.5% of the variation in biomarkers. The HR and 95% confidence interval (CI) for quartile 4 versus 1 of the HbA_1c+C peptide-based score and colorectal cancer was 1.30 (1.15-1.47), the hsCRP-based score was 1.35 (1.19-1.53), and the hsCRP, C-peptide, and HbA_1c-based score was 1.35 (1.19-1.52). The latter score was associated with non-CIMP tumors (HR_Q4vsQ1: 1.59; 95% CI: 1.17-2.16), but not CIMP-positive tumors (P _{heterogeneity} = 0.04).

CONCLUSIONS

These results further support hypotheses that systemic biomarkers of metabolic health-inflammation and abnormal glucose homeostasis-mediate part of the relationship between several energy balance-related modifiable factors and colorectal cancer risk.

IMPACT

Results support cancer prevention guidelines for maintaining a healthful body weight, consuming a healthful diet, and being physically active. More research is needed on these clusters of exposures with molecular phenotypes of tumors.

Development and validation of multivariable clinical diagnostic models to identify type 1 diabetes requiring rapid insulin therapy in adults aged 18-50 years

OBJECTIVE

To develop and validate multivariable clinical diagnostic models to assist distinguishing between type 1 and type 2 diabetes in adults aged 18-50.

DESIGN

Multivariable logistic regression analysis was used to develop classification models integrating five pre-specified predictor variables, including clinical features (age of diagnosis, body mass index) and clinical biomarkers (GADA and Islet Antigen 2 islet autoantibodies, Type 1 Diabetes Genetic Risk Score), to identify type 1 diabetes with rapid insulin requirement using data from existing cohorts.

SETTING

UK cohorts recruited from primary and secondary care.

PARTICIPANTS

1352 (model development) and 582 (external validation) participants diagnosed with diabetes between the age of 18 and 50 years of white European origin.

MAIN OUTCOME MEASURES

Type 1 diabetes was defined by rapid insulin requirement (within 3 years of diagnosis) and severe endogenous insulin deficiency (C-peptide <200 pmol/L). Type 2 diabetes was defined by either a lack of rapid insulin requirement or, where insulin treated within 3 years, retained endogenous insulin secretion (C-peptide >600 pmol/L at ≥5 years diabetes duration). Model performance was assessed using area under the receiver operating characteristic curve (ROC AUC), and internal and external validation.

RESULTS

Type 1 diabetes was present in 13% of participants in the development cohort. All five predictor variables were discriminative and independent predictors of type 1 diabetes (p<0.001 for all) with individual ROC AUC ranging from 0.82 to 0.85. Model performance was high: ROC AUC range 0.90 (95% CI 0.88 to 0.93) (clinical features only) to 0.97 (95% CI 0.96 to 0.98) (all predictors) with low prediction error. Results were consistent in external validation (clinical features and GADA ROC AUC 0.93 (0.90 to 0.96)).

CONCLUSIONS

Clinical diagnostic models integrating clinical features with biomarkers have high accuracy for identifying type 1 diabetes with rapid insulin requirement, and could assist clinicians and researchers in accurately identifying patients with type 1 diabetes.

Persistent C-peptide secretion in Type 1 diabetes and its relationship to the genetic architecture of diabetes

BACKGROUND

The objective of this cross-sectional study was to explore the relationship of detectable C-peptide secretion in type 1 diabetes to clinical features and to the genetic architecture of diabetes.

METHODS

C-peptide was measured in an untimed serum sample in the SDRNT1BIO cohort of 6076 Scottish people with clinically diagnosed type 1 diabetes or latent autoimmune diabetes of adulthood. Risk scores at loci previously associated with type 1 and type 2 diabetes were calculated from publicly available summary statistics.

RESULTS

Prevalence of detectable C-peptide varied from 19% in those with onset before age 15 and duration greater than 15 years to 92% in those with onset after age 35 and duration less than 5 years. Twenty-nine percent of variance in C-peptide levels was accounted for by associations with male gender, late age at onset and short duration. The SNP heritability of residual C-peptide secretion adjusted for gender, age at onset and duration was estimated as 26%. Genotypic risk score for type 1 diabetes was inversely associated with detectable C-peptide secretion: the most strongly associated loci were the HLA and INS gene regions. A risk score for type 1 diabetes based on the HLA DR3 and DQ8-DR4 serotypes was strongly associated with early age at onset and inversely associated with C-peptide persistence. For C-peptide but not age at onset, there were strong associations with risk scores for type 1 and type 2 diabetes that were based on SNPs in the HLA region but not accounted for by HLA serotype.

CONCLUSIONS

Persistence of C-peptide secretion varies widely in people clinically diagnosed as type 1 diabetes. C-peptide persistence is influenced by variants in the HLA region that are different from those determining risk of early-onset type 1 diabetes. Known risk loci for diabetes account for only a small proportion of the genetic effects on C-peptide persistence.

Type 1 diabetes defined by severe insulin deficiency occurs after 30 years of age and is commonly treated as type 2 diabetes

AIMS/HYPOTHESIS

Late-onset type 1 diabetes can be difficult to identify. Measurement of endogenous insulin secretion using C-peptide provides a gold standard classification of diabetes type in longstanding diabetes that closely relates to treatment requirements. We aimed to determine the prevalence and characteristics of type 1 diabetes defined by severe endogenous insulin deficiency after age 30 and assess whether these individuals are identified and managed as having type 1 diabetes in clinical practice.

METHODS

We assessed the characteristics of type 1 diabetes defined by rapid insulin requirement (within 3 years of diagnosis) and severe endogenous insulin deficiency (non-fasting C-peptide <200 pmol/l) in 583 participants with insulin-treated diabetes, diagnosed after age 30, from the Diabetes Alliance for Research in England (DARE) population cohort. We compared characteristics with participants with retained endogenous insulin secretion (>600 pmol/l) and 220 participants with severe insulin deficiency who were diagnosed under age 30.

RESULTS

Twenty-one per cent of participants with insulin-treated diabetes who were diagnosed after age 30 met the study criteria for type 1 diabetes. Of these participants, 38% did not receive insulin at diagnosis, of whom 47% self-reported type 2 diabetes. Rapid insulin requirement was highly predictive of severe endogenous insulin deficiency: 85% required insulin within 1 year of diagnosis, and 47% of all those initially treated without insulin who progressed to insulin treatment within 3 years of diagnosis had severe endogenous insulin deficiency. Participants with late-onset type 1 diabetes defined by development of severe insulin deficiency had similar clinical characteristics to those with young-onset type 1 diabetes. However, those with later onset type 1 diabetes had a modestly lower type 1 diabetes genetic risk score (0.268 vs 0.279; p < 0.001 [expected type 2 diabetes population median, 0.231]), a higher islet autoantibody prevalence (GAD-, islet antigen 2 [IA2]- or zinc transporter protein 8 [ZnT8]-positive) of 78% at 13 years vs 62% at 26 years of diabetes duration; (p = 0.02), and were less likely to identify as having type 1 diabetes (79% vs 100%; p < 0.001) vs those with young-onset disease.

CONCLUSIONS/INTERPRETATION

Type 1 diabetes diagnosed over 30 years of age, defined by severe insulin deficiency, has similar clinical and biological characteristics to that occurring at younger ages, but is frequently not identified. Clinicians should be aware that patients progressing to insulin within 3 years of diagnosis have a high likelihood of type 1 diabetes, regardless of initial diagnosis.

C-Peptide Decline in Type 1 Diabetes Has Two Phases: An Initial Exponential Fall and a Subsequent Stable Phase

OBJECTIVE

The decline in C-peptide in the 5 years after diagnosis of type 1 diabetes has been well studied, but little is known about the longer-term trajectory. We aimed to examine the association between log-transformed C-peptide levels and the duration of diabetes up to 40 years after diagnosis.

RESEARCH DESIGN AND METHODS

We assessed the pattern of association between urinary C-peptide/creatinine ratio (UCPCR) and duration of diabetes in cross-sectional data from 1,549 individuals with type 1 diabetes using nonlinear regression approaches. Findings were replicated in longitudinal follow-up data for both UCPCR (n = 161 individuals, 326 observations) and plasma C-peptide (n = 93 individuals, 473 observations).

RESULTS

We identified two clear phases of C-peptide decline: an initial exponential fall over 7 years (47% decrease/year [95% CI -51, -43]) followed by a stable period thereafter (+0.07%/year [-1.3, +1.5]). The two phases had similar durations and slopes in patients above and below the median age at diagnosis (10.8 years), although levels were lower in the younger patients irrespective of duration. Patterns were consistent in both longitudinal UCPCR (n = 162; ≤7 years duration: -48%/year [-55, -38]; >7 years duration -0.1% [-4.1, +3.9]) and plasma C-peptide (n = 93; >7 years duration only: -2.6% [-6.7, +1.5]).

CONCLUSIONS

These data support two clear phases of C-peptide decline: an initial exponential fall over a 7-year period, followed by a prolonged stabilization where C-peptide levels no longer decline. Understanding the pathophysiological and immunological differences between these two phases will give crucial insights into understanding β-cell survival.

Pathophysiology-based phenotyping in type 2 diabetes: A clinical classification tool

BACKGROUND

Type 2 diabetes may be a more heterogeneous disease than previously thought. Better understanding of pathophysiological subphenotypes could lead to more individualized diabetes treatment. We examined the characteristics of different phenotypes among 5813 Danish patients with new clinically diagnosed type 2 diabetes.

METHODS

We first identified all patients with rare subtypes of diabetes, latent autoimmune diabetes of adults (LADA), secondary diabetes, or glucocorticoid-associated diabetes. We then used the homeostatic assessment model to subphenotype all remaining patients into insulinopenic (high insulin sensitivity and low beta cell function), classical (low insulin sensitivity and low beta cell function), or hyperinsulinemic (low insulin sensitivity and high beta cell function) type 2 diabetes.

RESULTS

Among 5813 patients diagnosed with incident type 2 diabetes in the community clinical setting, 0.4% had rare subtypes of diabetes, 2.8% had LADA, 0.7% had secondary diabetes, 2.4% had glucocorticoid-associated diabetes, and 93.7% had WHO-defined type 2 diabetes. In the latter group, 9.7% had insulinopenic, 63.1% had classical, and 27.2% had hyperinsulinemic type 2 diabetes. Classical patients were obese (median waist 105 cm), and 20.5% had cardiovascular disease (CVD) at diagnosis, while insulinopenic patients were fairly lean (waist 92 cm) and 17.5% had CVD (P = 0.14 vs classical diabetes). Hyperinsulinemic patients were severely obese (waist 112 cm), and 25.5% had CVD (P < 0.0001 vs classical diabetes).

CONCLUSIONS

Patients clinically diagnosed with type 2 diabetes are a heterogeneous group. In the future, targeted treatment based on pathophysiological characteristics rather than the current "one size fits all" approach may improve patient prognosis.

Kill two birds with one stone: making multi-transgenic pre-diabetes mouse models through insulin resistance and pancreatic apoptosis pathogenesis

BACKGROUND

Type 2 diabetes is characterized by insulin resistance accompanied by defective insulin secretion. Transgenic mouse models play an important role in medical research. However, single transgenic mouse models may not mimic the complex phenotypes of most cases of type 2 diabetes.

METHODS

Focusing on genes related to pancreatic islet damage, peripheral insulin resistance and related environmental inducing factors, we generated single-transgenic (C/EBP homology protein, CHOP) mice (CHOP mice), dual-transgenic (human islet amyloid polypeptide, hIAPP; CHOP) mice (hIAPP-CHOP mice) and triple-transgenic (11β-hydroxysteroid dehydrogenase type 1, 11β-HSD1; hIAPP; CHOP) mice (11β-HSD1-hIAPP- CHOP mice). The latter two types of transgenic (Tg) animals were induced with high-fat high-sucrose diets (HFHSD). We analyzed the diabetes-related symptoms and histology features of the transgenic animals.

RESULTS

Comparing symptoms on the spot-checked points, we determined that the triple-transgene mice were more suitable for systematic study. The results of intraperitoneal glucose tolerance tests (IPGTT) of triple-transgene animals began to change 60 days after induction (p < 0.001). After 190 days of induction, the body weights (p < 0.01) and plasma glucose of the animals in Tg were higher than those of the animals in Negative Control (Nc). After sacrificed, large amounts of lipid were found deposited in adipose (p < 0.01) and ectopically deposited in the non-adipose tissues (p < 0.05 or 0.01) of the animals in the Tg HFHSD group. The weights of kidneys and hearts of Tg animals were significantly increased (p < 0.01). Serum C peptide (C-P) was decreased due to Tg effects, and insulin levels were increased due to the effects of the HFHSD in the Tg HFHSD group, indicating that damaged insulin secretion and insulin resistance hyperinsulinemia existed simultaneously in these animals. The serum corticosterone of Tg was slightly higher than those of Nc due to the effects of the 11βHSD-1 transgene and obesity. In Tg HFHSD, hepatic adipose deposition was more severe and the pancreatic islet area was enlarged under compensation, accompanying apoptosis. In the transgenic control diet (Tg ControlD) group, hepatic adipose deposition was also severe, pancreatic islets were damaged, and their areas were decreased (p < 0.05), and apoptosis of pancreatic cells occurred. Taken together, these data show the transgenes led to early-stage pathological changes characteristic of type 2 diabetes in the triple-transgene HFHSD group. The disease of triple-transgenic mice was more severe than that of dual or single-transgenic mice.

CONCLUSION

The use of multi-transgenes involved in insulin resistance and pancreatic apoptosis is a better way to generate polygene-related early-stage diabetes models.

Immunological markers as predictors of developing steroid-induced diabetes mellitus in pemphigus vulgaris patients: An observational study

The aim of this study was to evaluate the clinical importance of autoantibodies in pemphigus vulgaris patients who developed steroid-induced diabetes mellitus (SID) because of the glucocorticoid therapy of pemphigus.A total of 137 patients with pemphigus vulgaris were studied. Patients with SID and pemphigus were compared with those that had only pemphigus. The variables recorded were: age at diagnosis, sex, body mass index, presence of diabetes mellitus (DM), cumulative cortisone dose, treatment duration, value of anti-desmoglein 1 and 3, and anti-glutamic acid decarboxylase autoantibodies.A total of 31 patients (22.62%) that developed steroid-induced DM were identified. Anti-glutamic acid decarboxylase autoantibodies were positive in 20.75% of patients with pemphigus vulgaris and in 25.75% of patients with pemphigus vulgaris and SID.The overall anti-glutamic acid decarboxylase autoantibodies prevalence in pemphigus patients was high, and the risk of developing DM in patients with pemphigus remains a serious problem, being associated with increased risk of mortality.

Beta cell function after intensive subcutaneous insulin therapy or intravenous insulin infusion at onset of type 1 diabetes in children without ketoacidosis

BACKGROUND

Our aim was to see if IV insulin therapy at diagnosis preserves beta-cell function better than multiple subcutaneous (SC) injections.

METHODS

Fifty-four children 9.9 ± 3.5 years (range 2.8-14.9) without ketoacidosis were included in a 2 years, randomized multicenter study with insulin SC or 48 to 72 hours IV initially. Thirty-three (61%) were boys, 22 (41%) were pubertal. Forty-eight subjects completed 12 months follow-up and 43 completed 24 months. At 1, 6, 12, and 24 months, hemoglobin A1c (HbA1c), C-peptide and insulin/kg/24 h were measured. At 24 months, a mixed-meal tolerance test (MMTT) was performed.

RESULTS

HbA1c at diagnosis was 10.7%, (93 mmol/mol) for IV, 10.7%, (94 mmol/mol) for SC. During the first 2 full days of insulin therapy, mean plasma glucose was 8.2 mmol/L for IV, 9.5 for SC (P = .025). Mean insulin dose was 1.5 U/kg/d for IV vs 1.0 for SC (P = .001). Sixteen (7 in IV, 9 in SC group) started with insulin pumps during the follow-up. At 24 months, we saw no significant differences: HbA1c (7.5%, 58 mmol/mol, for IV, 7.2%, 55 mmol/mol, for SC; ns), insulin doses (0.79 vs 0.88 U/kg/d; ns), fasting C-peptide (0.08 vs 0.12 nmol/L; ns), maximal MMTT response (0.19 vs 0.25 nmol/L; ns) and AUC (18.26 vs 23.9 nmol/L*min; ns). Peak C-peptide >0.2 nmol/L in the combined IV and SC groups correlated significantly with HbA1c and C-peptide at onset in a multiple regression.

CONCLUSION

Residual beta cell function at 2 years seems to be independent from initial insulin regimens but related to HbA1c and C-peptide at onset.

Random non-fasting C-peptide testing can identify patients with insulin-treated type 2 diabetes at high risk of hypoglycaemia

AIMS/HYPOTHESIS

The aim of this study was to determine whether random non-fasting C-peptide (rCP) measurement can be used to assess hypoglycaemia risk in insulin-treated type 2 diabetes.

METHODS

We compared continuous glucose monitoring-assessed SD of blood glucose and hypoglycaemia duration in 17 patients with insulin-treated type 2 diabetes and severe insulin deficiency (rCP < 200 pmol/l) and 17 matched insulin-treated control patients with type 2 diabetes but who had preserved endogenous insulin (rCP > 600 pmol/l). We then assessed the relationship between rCP and questionnaire-based measures of hypoglycaemia in 256 patients with insulin-treated type 2 diabetes and a comparison group of 209 individuals with type 1 diabetes.

RESULTS

Continuous glucose monitoring (CGM)-assessed glucose variability and hypoglycaemia was greater in individuals with rCP < 200 pmol/l despite similar mean glucose. In those with low vs high C-peptide, SD of glucose was 4.2 (95% CI 3.7, 4.6) vs 3.0 (2.6, 3.4) mmol/l (p < 0.001). In the low-C-peptide vs high-C-peptide group, the proportion of individuals experiencing sustained hypoglycaemia ≤ 4 mmol/l was 94% vs 41% (p < 0.001), the mean rate of hypoglycaemia was 5.5 (4.4, 6.7) vs 2.1 (1.4, 2.9) episodes per person per week (p = 0.004) and the mean duration was 630 (619, 643) vs 223 (216, 230) min per person per week (p = 0.01). Hypoglycaemia ≤ 3 mmol/l was infrequent in individuals with preserved C-peptide (1.8 [1.2, 2.6] episodes per person per week vs 0.4 [0.1, 0.8] episodes per person per week for low vs high C-peptide, p = 0.04) and only occurred at night. In a population-based cohort with insulin-treated type 2 diabetes, self-reported hypoglycaemia was twice as frequent in those with rCP < 200 pmol/l (OR 2.0, p < 0.001) and the rate of episodes resulting in loss of consciousness or seizure was five times higher (OR 5.0, p = 0.001). The relationship between self-reported hypoglycaemia and C-peptide was similar in individuals with type 1 and type 2 diabetes.

CONCLUSIONS/INTERPRETATION

Low rCP is associated with increased glucose variability and hypoglycaemia in patients with insulin-treated type 2 diabetes and represents a practical, stable and inexpensive biomarker for assessment of hypoglycaemia risk.

A Practical Review of C-Peptide Testing in Diabetes

C-peptide is a widely used measure of pancreatic beta cell function. It is produced in equimolar amounts to endogenous insulin but is excreted at a more constant rate over a longer time. Methods of estimation include urinary and unstimulated and stimulated serum sampling. Modern assays detect levels of c-peptide which can be used to guide diabetes diagnosis and management. We explore the evidence behind the various tests available. We recommend the glucagon stimulation c-peptide testing owing to its balance of sensitivity and practicality. C-peptide levels are associated with diabetes type and duration of disease. Specifically a c-peptide level of less than 0.2 nmol/l is associated with a diagnosis of type 1 diabetes mellitus (T1DM). C-peptide level may correlate with microvascular and macrovascular complications and future use of insulin therapy, as well as likely response to other individual therapies. We explore the potential uses of c-peptide measurement in clinical practice.

Successful Withdrawal of Insulin Therapy After Post-Treatment Clearance of Hepatitis C Virus in a Man with Type 2 Diabetes

Patient: Male, 55

Final Diagnosis: Hepatitis C

Symptoms: Icterus

Medication: —

Clinical Procedure: —

Specialty: Endocrinology and Metabolic