The influence of body mass index and age on C-peptide at the diagnosis of type 1 diabetes in children who participated in the diabetes prevention trial-type 1

Type 1 diabetes presenting in adults: Trends, diagnostic challenges and unique features

Type 1 diabetes (T1D) has been historically regarded as a childhood-onset disease; however, recent epidemiological data indicate that adult-onset T1D accounts for a substantial proportion of cases worldwide. There is evidence that adult-onset T1D is associated with the classic T1D triad of elevated genetic risk, the presence of islet-specific autoantibodies and progression to severe insulin deficiency. In this article, we review our understanding of the commonalities and differences between childhood and adult-onset T1D, and we highlight significant knowledge gaps in our understanding of the diagnosis, incidence, trajectory and treatment of adult-onset T1D. Compared to children, adults presenting with T1D exhibit differences in genetic risk, immunologic profiles and metabolic outcomes, including differences in the type and number of autoantibodies present, genetic associations and total genetic burden, rates of C-peptide decline, the persistence of C-peptide in long-duration disease and glycaemic control. In addition, obesity and metabolic syndrome are increasingly common in adults, which not only blurs the clinical distinction of adult-onset T1D from type 2 diabetes (T2D) but also likely contributes to differences in metabolic outcomes and rates of progression. Because T2D is so prevalent in the adult population, adult-onset T1D is misclassified as T2D in at least one in three cases, leading to delays in appropriate treatment. Current diagnostic tools, including autoantibody testing and C-peptide measurement, are underutilised or lack specificity in distinguishing adult-onset T1D from atypical T2D. Additionally, the impact of different responses to disease-modifying therapy between adults and children is unclear. Addressing these knowledge gaps requires expanded epidemiological studies, diverse patient registries and refined classification criteria to improve early detection and treatment strategies. A deeper understanding of adult-onset T1D will be critical to reduce the burden of misdiagnosis, lead to earlier diagnosis and treatment and optimise population-based screening approaches in this under-recognised population. PLAIN LANGUAGE SUMMARY: Type 1 diabetes (T1D) is an autoimmune disease that causes metabolic and nutritional complications due to the destruction of insulin-producing pancreatic β cells. T1D was formerly known as "juvenile diabetes" because it was assumed that most cases occurred in childhood; however, recent epidemiological data show that nearly half of all T1D cases are diagnosed in adulthood. Despite the high prevalence of adult-onset T1D, there are challenges with correctly diagnosing T1D in adulthood, and significant knowledge gaps remain regarding the incidence, trajectory, and treatment of adult-onset T1D. In this article, we summarize the current understanding of commonalities and differences between childhood and adult-onset T1D. Particularly, we highlight age-related differences in genetic risk, immunologic profiles, and metabolic outcomes and complications. Finally, we highlight key gaps in our understanding of adult-onset T1D that need to be addressed to reduce the burden of misdiagnosis and allow for better screening and treatment of T1D in adulthood.

Fasting plasma C-peptide correlates with body mass index, hsCRP, apolipoprotein B, and other atherogenic lipids in healthy individuals

C-peptide has a complex role in human physiology, but its effects are not fully understood. Studies have shown a protective impact against diabetic complications, but also that C-peptide levels associate with cardiovascular events. Among the many applications to assess cardiovascular risk, circulating lipids are widely used, and one of the strongest biomarkers is apolipoprotein B. The aim of this investigation was to study the association of C-peptide with markers of metabolic, inflammatory, or cardiovascular alterations in a limited group of healthy individuals. Body mass index (BMI), lipids, and other plasma markers were studied in 28 consecutive healthy individuals within the age of 30-50 years. The results showed significant positive correlations between C-peptide and BMI (r = 0.498; p = 0.007); hsCRP (r = 0.530; p = 0.004); triglycerides (r = 0.530; p = 0.005); cholesterol (r = 0.507; p = 0.006), LDL-cholesterol (r = 0.550; p = 0.002), LDL/HDL ratio (r = 0.460; p = 0.014); apoB (r = 0.622; p < 0.001), apoB/apoA1 ratio (r = 0.563; p = 0.002); and non-HDL cholesterol (r = 0.566; p = 0.002). According to BMI values, 16 of the 28 individuals were overweight (BMI >25.0 kg/m2). If overweight individuals were excluded, C-peptide did only correlate with apoB (r = 0.636; p = 0.026). To conclude, C-peptide within normal levels associate with BMI and atherogenic lipids in healthy individuals, and apoB associate with C-peptide even at normal weight. These results suggest that C-peptide can be an early additional cardiovascular risk marker.

Pubertal stage significantly and independently impacts C-peptide levels at type 1 diabetes diagnosis along with body mass index and age

Assessment of beta-cell function in type 1 diabetes (T1D) has important implications in both clinical and research settings. Studies demonstrating the extent to which puberty influences C-peptide levels are scarce. The aim of this study was to evaluate the influence of pubertal stage, along with age and body mass index (BMI), on multiple C-peptide measures at T1D diagnosis. This study included 275 consecutive children aged between 1 and 18 years with newly diagnosed T1D. Fasting, prandial, and area under the curve (AUC) C-peptide, estimated using fasting and prandial C-peptide levels, were analyzed. Generalized linear regression models were utilized. Median age at diagnosis was 7.9 (1.1-17.3) years, and mean BMI standard deviation score (SDS) was - 0.4 ± 1.4. Of the patients, 66% were prepubertal. Median fasting and prandial C-peptide levels at diagnosis were 0.26 (0.05-1.8) ng/mL and 0.43 (0.05-3) ng/mL, respectively. Fasting C-peptide was almost perfectly correlated with prandial C-peptide (rs = 0.80, P < 0.001). Fasting, prandial, and AUC C-peptide were positively related with BMI SDS, age, and pubertal stage at diagnosis (P < 0.001 for all). All the associations persisted when the variables were included as independent variables in regression models.

CONCLUSIONS

Pubertal stage significantly and independently impacts C-peptide levels at T1D diagnosis along with body mass index and age. The adjustments demonstrating the extent to which puberty influences C-peptide levels in new-onset T1D are presented. Our observations underline the existence of distinct endotypes of T1D characterized by differing immunopathological courses.

WHAT IS KNOWN

• Throughout the evaluation of beta-cell function at T1D diagnosis, it is essential to consider the factors influencing C-peptide levels.

WHAT IS NEW

• While age and BMI at diagnosis are associated with beta-cell function, our findings set the stage for a greater understanding of the disease process with additional findings regarding puberty, supporting the existence of endotypes of T1D.

Clinical features, biomarkers and diabetic ketoacidosis at diagnosis of type 1 diabetes among children and adolescents in Sana'a, Yemen

INTRODUCTION

There is little published information on type 1 diabetes (T1D) in children in Yemen. We aimed to identify the clinical characteristics, biomarkers and diabetic ketoacidosis (DKA) at diagnosis of T1D among children and adolescents in a diabetes centre in Sana'a, Yemen.

METHODS

A total of 485 children and adolescents aged ≤18 years diagnosed with T1D during the period 2010-2020 were included in the study. The variables investigated were demographic and clinical characteristics, biomarkers, subtypes of T1D, and the risk factors for severe DKA at diagnosis.

RESULTS

At diagnosis, children aged <10 years compared with those aged ≥10 years had higher mean plasma glucose (p<0.001) and mean HbA1c (p=0.026), and lower mean C-peptide (pmol/L) (p=0.019), and a higher frequency of DKA at diagnosis than older children (p<0.001). A majority of the study population (383, 79%) presented in DKA . Children aged <10 years presenting with DKA had significantly longer median appraisal interval (p=0.009) and median total diagnosis interval (p=0.025), and significantly lower mean C-peptide (p=0.001) as compared with their peers without DKA. The prevalence of autoantibody-negative 'idiopathic' T1D was 36 (32%) of the total number tested for autoantibody and familial T1D 61 (12.6%) of all the study population.

CONCLUSION

In Yemen children aged <10 years with new-onset T1D frequently faced the challenge of a delay in diagnosis and treatment initiation, with severe hyperglycaemia and a higher risk of DKA at diagnosis.

Quantifying beta cell function in the preclinical stages of type 1 diabetes

Clinically symptomatic type 1 diabetes (stage 3 type 1 diabetes) is preceded by a pre-symptomatic phase, characterised by progressive loss of functional beta cell mass after the onset of islet autoimmunity, with (stage 2) or without (stage 1) measurable changes in glucose profile during an OGTT. Identifying metabolic tests that can longitudinally track changes in beta cell function is of pivotal importance to track disease progression and measure the effect of disease-modifying interventions. In this review we describe the metabolic changes that occur in the early pre-symptomatic stages of type 1 diabetes with respect to both insulin secretion and insulin sensitivity, as well as the measurable outcomes that can be derived from the available tests. We also discuss the use of metabolic modelling to identify insulin secretion and sensitivity, and the measurable changes during dynamic tests such as the OGTT. Finally, we review the role of risk indices and minimally invasive measures such as those derived from the use of continuous glucose monitoring.

Body mass index and partial remission in 119 children with type 1 diabetes-a 6-year observational study

Background/objective

This long-term study aimed to analyze the associations between BMI Z-score, HbA1c, and daily insulin requirement (DIR) and the prevalence and duration of partial remission (PR) in children and adolescents with type 1 diabetes (T1D).

Methods

After retrieving retrospective data for 195 patients from their health records at 24, 48, and 72 months after T1D diagnosis, the study group was comprised of 119 (57 girls) children with a complete dataset for all 6 years. PR was defined according to the ISPAD guidelines. Analyses were carried out in the whole group and subgroups according to PR duration: no PR at all (NPR), PR lasting less than 2 years (PR < 2), and PR at least 2 years (PR ≥ 2).

Results

PR was observed in 63% of the patients (78.9% of overweight and 100% of obese patients). NPR patients showed the lowest mean initial BMI Z-score [-0.65 ± 1.29 vs. 0.02 ± 1.42, (PR < 2), p = 0.01 and vs. 0.64 ± 1.43 (PR ≥ 2), p = 0.17]. The dissimilarity in BMI across patients declined over time. Within the NPR group, the initial mean BMI Z-score significantly increased within the first 2 years (unadjusted p < 0.001) and remained constant afterward. In the PR <2 group, the highest increase in BMI Z-score occurred after 4 years (p < 0.001) and then decreased (p = 0.04). In the PR ≥2, the BMI Z-score slightly decreased within the first 2 years (p = 0.02), then increased (p = 0.03) and remained unchanged for the last 2 years. Six years after T1D started, the mean DIRs do not differ among the patient groups (ANOVA p = 0.272).

Conclusion

During 6 years of follow-up, PR occurred in almost two-thirds of the studied children including almost all overweight and obese children. We observed a gradual normalization of the BMI Z-score at the end of the follow-up. BMI Z-score increased slightly in children with no remission initially but remained later constant until the end of observation. In both remitter groups, the increase in BMI Z-score appeared later when the protective honeymoon period ended. Regardless of BMI Z-score, the β-cell destruction process progresses, and after 6 years, the DIR is similar for all patients.

Changes in C-Peptide Values in Children with Type 1 Diabetes - a Three-Year Study

Background: C-peptide is used as an important indicator of residual insulin secretion in patients diagnosed with type 1 diabetes mellitus (T1DM) and treated with insulin. Aim:We have aimed to monitor the serum C-peptide (CP) levels during the first three years after diagnosis of T1DM in a cohort of children admitted to the Diabetes Department of "M. S. Curie" Emergency Clinical Hospital for Children, Bucharest, Romania, and to investigate the factors that could influence the rate of decline in its secretion. Method:We conducted a longitudinal, retrospective cohort study on a group of 215 children and adolescents who met the inclusion criteria and were monitored in our clinic over the course of a long period of time. We analyzed several parameters, including fasting serum CP values at diagnosis and yearly throughout T1DM evolution, the severity of diabetic ketoacidosis (DKA) at onset, HbA1c at diagnosis, family history of T1DM/T2DM, patient gender and presence of concurrent acute infectious disease at diagnosis, with the purpose of evaluating their influence on the preservation of endogenous insulin secretion. Based on serum CP value measured three years after T1DM onset, patients were divided into two groups: group 1, with low insulin residual secretion (CP < 0.6 ng/mL), and group 2, with preserved insulin residual secretion (CP ≥0.6 ng/mL) Results:At the moment of diagnosis, patients in group 1 were younger than those in group 2 (6.03 ± 3.54 years and 9.76 ± 2.75 years, respectively). The proportion of children with diabetic ketoacidosis (DKA) at onset was greater in group 1 (68% of patients) than group 2, in which the majority of subjects (60%) did not have DKA. The C-peptide value at diagnosis was significantly lower (0.55 ± 0.36 ng/mL) among patients in group 1 than those in group 2 (1.11 ± 0.59 ng/mL). In group 1 there was a higher proportion of patients (65%) with acute infectious disease at onset. Family history of T1DM/T2DM was associated with a more rapid decline in CP values. Our data showed no correlation between CP levels monitored for three years and HbA1c at diagnosis and no association with the gender of each patient. Conclusion:Patients with higher CP concentrations at diagnosis maintained increased values (> 0.6 ng/mL) three years after disease onset. Younger children had a faster decline of CP secretion during the first three years following diabetes diagnosis. In patients with severe symptoms (DKA) and associated infectious disease at onset, a risk of rapid CP decline was found.

Excessive BMI is associated with higher C-peptide level at recognition but also with its greater loss in two years clinical observation in children with new onset type 1 diabetes

Introduction

The prevalence of obesity in general pediatric population increases without sparing children with T1D. We intended to find factors associated with the possibility of preserving endogenous insulin secretion in individuals with long-standing T1D. At onset, higher BMI is associated with higher C-peptide level, which may indicate to be one of the favorable factors involved in preserving residual β-cell function. The study determines the influence of BMI on C-peptide secretion in children newly diagnosed with T1D in two years observation.

Methods

We assessed the possible relationship between selected pro- and anti-inflammatory cytokines, body mass at recognition and β-cell function status. 153 pediatric patients with newly diagnosed T1D were divided into quartiles according to BMI-SDS index. We separated a group consisted of patients with BMI-SDS >1. Participants were followed up for two years and examined for changes in body weight, HbA1c, and insulin requirement. C-peptide was assessed at baseline and after two years. We evaluated the patients' levels of selected inflammatory cytokines at baseline.

Results

Subjects with higher BMI-SDS presented higher serum C-peptide levels and lower insulin requirements at diagnosis than children with lower body weight. The two-year follow-up showed that C-peptide levels of obese patients dropped more rapidly than in children with BMI-SDS within normal limits. The group with BMI-SDS >1 showed the greatest decrease in C-peptide level. Despite statistically insignificant differences in HbA1c at diagnosis between the study groups, in the fourth quartile and BMI-SDS >1 groups, HbA1c as well as insulin requirements increased after two years. The levels of cytokines varied the most between BMI-SDS <1 and BMI-SDS >1 groups and were significantly higher within BMI-SDS >1 group.

Discussion

Higher BMI, associated with enhanced levels of inflammatory cytokines, relates to preservation of C-peptide at T1D recognition in children but is not beneficial in the long term. A decrease in C-peptide levels combined with an increase in insulin requirements and in HbA1c among patients with high BMI occur, which may indicate a negative effect of excessive body weight on the long term preservation of residual β-cell function. The process seems to be mediated by inflammatory cytokines.

Efficacy of epalrestat combined with alprostadil for diabetic nephropathy and its impacts on renal fibrosis and related factors of inflammation and oxidative stress

OBJECTIVE

To explore the efficacy of epalrestat (Ep) combined with alprostadil (Alp) in the treatment of diabetic nephropathy (DN) and its impacts on renal fibrosis (RF) and inflammation and oxidative stress (OS)-related factors.

METHODS

In this retrospective study, 120 patients with DN treated in the Cangzhou Central Hospital from January 2020 to January 2021 were selected as the research subjects. Among them, 80 cases treated with Ep combined with Alp were assigned to group A, and the rest 40 patients treated with Alp only were assigned to group B. The two groups were compared with respect to the following items: serum OS indexes (malondialdehyde, MDA; superoxide dismutase, SOD; total antioxidant capacity, TAOC), inflammatory factors (tumor necrosis factor-α, TNF-α; interleukin-2, IL-2), RF index transforming growth factor-β1 (TGF-β1), urinary protein indexes (urinary albumin excretion, UAE; serum albumin, ALB), blood glucose (fasting blood glucose, FBG), fasting C-peptide, postprandial 2hC peptide levels, overall response rate (ORR) and incidence of adverse reactions.

RESULTS

Compared with group B, the levels of MDA, TNF-α, IL-2 and TGF-β1 were lower, while SOD and TAOC were higher in group A. In addition, ALB was higher, while UAE and FBG were lower in group A as compared with group B. Moreover, group A had a higher ORR and fewer adverse reactions as compared with group B.

CONCLUSION

The combined therapy of Ep and Alp is more effective in the treatment of DN. This combination can effectively reduce RF and better alleviate inflammation and OS.

The Influence of Different Types of Diabetes on Vascular Complications

The final outcome of diabetes is chronic complications, of which vascular complications are the most serious, which is the main cause of death for diabetic patients and the direct cause of the increase in the cost of diabetes. Type 1 and type 2 diabetes are the main types of diabetes, and their pathogenesis is completely different. Type 1 diabetes is caused by genetics and immunity to destroy a large number of β cells, and insulin secretion is absolutely insufficient, which is more prone to microvascular complications. Type 2 diabetes is dominated by insulin resistance, leading to atherosclerosis, which is more likely to progress to macrovascular complications. This article explores the pathogenesis of two types of diabetes, analyzes the pathogenesis of different vascular complications, and tries to explain the different trends in the progression of different types of diabetes to vascular complications, in order to better prevent diabetes and its vascular complications.

Predictors of Glycemic Outcomes at 1 Year Following Pediatric Total Pancreatectomy With Islet Autotransplantation

OBJECTIVE

Total pancreatectomy with islet autotransplantation (TPIAT) is indicated to alleviate debilitating pancreas-related pain and mitigate diabetes in patients with acute recurrent and chronic pancreatitis when medical/endoscopic therapies fail. Our aim was to evaluate predictors of insulin requirement at 1 year following TPIAT in a cohort of children.

RESEARCH DESIGN AND METHODS

This was a review of 43 pediatric patients followed after TPIAT for 1 year or longer. Primary outcome was insulin use at 1 year, categorized as follows: insulin independent, low insulin requirement (<0.5 units/kg/day), or high insulin requirement (≥0.5 units/kg/day).

RESULTS

At 1 year after TPIAT, 12 of 41 (29%) patients were insulin independent and 21 of 41 (51%) had low and 8 of 41 (20%) had high insulin requirement. Insulin-independent patients were younger than those with low and high insulin requirement (median age 8.2 vs. 14.6 vs. 13.1 years, respectively; P = 0.03). Patients with insulin independence had a higher number of transplanted islet equivalents (IEQ) per kilogram body weight (P = 0.03) and smaller body surface area (P = 0.02), compared with those with insulin dependence. Preoperative exocrine insufficiency was associated with high insulin requirement (P = 0.03). Higher peak C-peptide measured by stimulated mixed-meal tolerance testing (MMTT) at 3 and 6 months post-TPIAT was predictive of lower insulin requirement at 1 year (P = 0.006 and 0.03, respectively).

CONCLUSIONS

We conclude that insulin independence following pediatric TPIAT is multifactorial and associated with younger age, higher IEQ per kilogram body weight transplanted, and smaller body surface area at time of operation. Higher peak C-peptide measured by MMTT following TPIAT confers a higher likelihood of low insulin requirement.

Partial remission in children and adolescents with type 1 diabetes: an analysis based on the insulin dose-adjusted hemoglobin A1c

OBJECTIVES

Most patients with type 1 diabetes (T1D) experience a transient phase of partial remission (PR). This study aimed to identify the demographic and clinical factors associated with PR.

METHODS

This was a longitudinal retrospective cohort study of 133 children and adolescents with T1D. PR was defined by the gold standard insulin dose-adjusted hemoglobin A1c (HbA1c) (IDAA1c) of ≤9.

RESULTS

Remission was observed in 77 (57.9%) patients. At diagnosis, remitters had significantly higher pH (7.3 ± 0.12 vs. 7.23 ± 0.15, p=0.003), higher C-peptide levels (0.45 ± 0.31 ng/mL vs. 0.3 ± 0.22, p=0.003), and they were significantly older (9.3 ± 3.6 years vs. 7.3 ± 4.2, p=0.008) compared with non-remitters. PR developed more frequently in patients without diabetic ketoacidosis (DKA) (p=0.026) and with disease onset after age 5 (p=0.001). Patients using multiple daily insulin regimen were more likely to experience PR than those treated with a twice daily regimen (63.9 vs. 32%, p=0.004). Only age at onset was an independent predictor of PR (OR: 1.12, 95% CI: 1-1.25; p=0.044). Remitters had lower HbA1c levels and daily insulin requirement from diagnosis until one year after diagnosis (p<0.001). PR recurred in 7 (9%) patients. The daily insulin requirement at three months was lower in remitters with PR recurrence compared to those without (0.23 ± 0.14 vs. 0.4 ± 0.17 U/kg/day, p=0.014).

CONCLUSIONS

Addressing factors associated with the occurrence of PR could provide a better comprehension of metabolic control in T1D. The lack of DKA and higher C-peptide levels may influence PR, but the main factor associated with PR presence was older age at onset. PR may recur in a small proportion of patients.

Clinical and genetic features of maturity-onset diabetes of the young in pediatric patients: a 12-year monocentric experience

BACKGROUND

A retrospective observational study was conducted to assess the prevalence of maturity onset diabetes of the young (MODY) in a large paediatric population of Southern Italy newly diagnosed with diabetes. Clinical and genetic features of the identified MODY patients were also described.

METHODS

Genetic testing was performed in children and adolescents newly diagnosed with diabetes who presented autoantibody negativity and fasting C-peptide levels ≥ 0.8 ng/mL. Patients with a low insulin daily dose and optimal glycaemic control after two years from diabetes onset were also investigated for monogenic diabetes, regardless of their autoimmunity status and/or C-peptide levels.

RESULTS

A prevalence of 6.5% of MODY was found. In particular, glucokinase-MODY was the most common type of MODY. The mean age at diagnosis was 9.1 years. Clinical presentation and biochemical data were heterogeneous also among patients belonging to the same MODY group.

CONCLUSIONS

We found a relatively high prevalence of MODY among paediatric patients with a new diagnosis of diabetes in comparison to literature data. Our findings highlight that a more detailed clinical evaluation along with easier and less expensive approachability to genetic testing may allow diagnosing an increasing number of MODY cases. A correct, prompt diagnosis is crucial to choose the most appropriate treatment and offer adequate genetic counselling.

Factors Associated With the Decline of C-Peptide in a Cohort of Young Children Diagnosed With Type 1 Diabetes

CONTEXT

Understanding factors involved in the rate of C-peptide decline is needed to tailor therapies for type 1 diabetes (T1D).

OBJECTIVE

Evaluate factors associated with rate of C-peptide decline after a T1D diagnosis in young children.

DESIGN

Observational study.

SETTING

Academic centers.

PARTICIPANTS

A total of 57 participants from the Environmental Determinants of Diabetes in the Young (TEDDY) study who were enrolled at 3 months of age and followed until T1D, and 56 age-matched children diagnosed with T1D in the community.

INTERVENTION

A mixed meal tolerance test was used to measure the area under the curve (AUC) C-peptide at 1, 3, 6, 12, and 24 months postdiagnosis.

OUTCOME

Factors associated with rate of C-peptide decline during the first 2 years postdiagnosis were evaluated using mixed effects models, adjusting for age at diagnosis and baseline C-peptide.

RESULTS

Adjusted slopes of AUC C-peptide decline did not differ between TEDDY subjects and community controls (P = 0.21), although the former had higher C-peptide baseline levels. In univariate analyses combining both groups (n = 113), younger age, higher weight and body mass index z-scores, female sex, an increased number increased number of islet autoantibodies, and IA-2A or ZnT8A positivity at baseline were associated with a higher rate of C-peptide loss. Younger age, female sex, and higher weight z-score remained significant in multivariate analysis (all P < 0.02). At 3 months after diagnosis, higher HbA1c became an additional independent factor associated with a higher rate of C-peptide decline (P < 0.01).

CONCLUSION

Younger age at diagnosis, female sex, higher weight z-score, and HbA1c were associated with a higher rate of C-peptide decline after T1D diagnosis in young children.

A little help from residual β cells has long-lasting clinical benefits

Following type 1 diabetes (T1D) diagnosis, declining C-peptide levels reflect deteriorating β cell function. However, the precise C-peptide levels that indicate protection from severe hypoglycemia remain unknown. In this issue of the JCI, Gubitosi-Klug et al. studied participants from the landmark and ongoing Diabetes Control and Complications Trial (DCCT) and the Epidemiology of Diabetes Interventions and Complications (EDIC) study that had long-standing (about 35 years) T1D. The authors correlated severe hypoglycemia and other disease outcomes with residual C-peptide levels. While C-peptide secretion failed to associate with hemoglobin A1c (HbA1c) or microvascular complications, C-peptide levels greater than 0.03 nmol/L were linked with fewer episodes of severe hypoglycemia. These findings suggest that efforts to preserve finite β cell function early in T1D can have meaningful, long-standing health benefits for patients.

Surrogate markers and predictors of endogenous insulin secretion in children and adolescents with type 1 diabetes

BACKGROUND

No studies have examined endogenous insulin secretion in pediatric patients with type 1 diabetes in China using the gold-standard mixed-meal tolerance test. Because the latter is labor-intensive, we examined simpler surrogate markers of endogenous insulin secretion in Chinese youth, as previously reported for a European population.

METHODS

Participants were 57 children and adolescents with type 1 diabetes aged 4.4-16.8 years (56% females). We performed 120-minute mixed-meal tolerance tests with serum C-peptide (CP) measurements every 30 minutes. Severe insulin deficiency (SID) was defined as CP peak < 0.2 nmol/L. Urine CP and creatinine levels were measured at 0 and 120 minutes.

RESULTS

Twenty-five (44%) patients had SID. Fasting CP levels missed one case (96% sensitivity) with no false positives (100% specificity). While the 120-minute urine CP/creatinine had 100% sensitivity, it yielded markedly lower specificity (63%). Every 1-year increase in diabetes duration and 1-year decrease in age at diagnosis were associated with 37% (P < 0.001) and 20% (P = 0.005) reductions in serum CP area-under-the-curve, respectively. Thus, 86% of children aged < 5 years had SID compared to none among patients aged ≥ 11 years.

CONCLUSIONS

Simple fasting CP measurements could be used to detect most SID cases in Chinese youth with type 1 diabetes. Fasting CP is a far more reliable measure of endogenous insulin secretion than the more commonly used insulin dose. Therefore, it could more precisely determine insulin secretory capacity to target those who could benefit, if treatments to preserve residual insulin secretion are developed.

Complicated curve association of body weight at diagnosis with C-peptide in children and adults with new-onset type 1 diabetes

AIM

To investigate the association of body mass index (BMI) or BMI z-score (BMIz) at diagnosis with β-cell function in new-onset type 1 diabetes (T1D) patients in children and adults.

METHODS

This was a retrospective cohort study; 256 children (<18 years) and 245 adults (≥18 years) with less than 1-year duration were recruited and followed for 4 years with an interval of 12 months. Smooth curve fitting, a two-piecewise linear model, and Cox proportional hazards models were utilized to investigate the influence of BMI/BMIz on C-peptide levels.

RESULTS

Heavier patients (BMIz ≥ -1 in children and BMI in adults ≥20.2 kg/m² ) had greater C-peptide with a complicated J curve in all age groups after adjustment for age of onset, sex, and disease duration. Moreover, after 4 years of follow-up, patients with higher BMI/BMIz had a lower risk of β-cell failure (HR = 0.7; 95% CI, 0.6-1.0; P = .026). However, no association was found between baseline BMI/BMIz at diagnosis and C-peptide rate of decline during 1 year follow-up.

CONCLUSION

Association between BMI/BMIz and C-peptide in T1D followed a complicated J curve pattern, and heavier patients had greater C-peptide at diagnosis and a lower risk of β-cell failure at 4 years, suggesting that baseline BMI is a useful predictor for β-cell function in patients with T1D.

Tapering decay of β-cell function in Chinese patients with autoimmune type 1 diabetes: A four-year prospective study

BACKGROUND

This study investigated the natural progression of β-cell function in Chinese autoimmune type 1 diabetic (T1D) patients and clarified factors possibly influencing the course of the disease.

METHODS

The natural progression of β-cell function of 325 newly diagnosed Chinese autoimmune T1D patients was assessed by fasting and postprandial C-peptide (FCP and PCP, respectively) levels. β-Cell function failure was defined as FCP <50 pM and PCP <100 pM, whereas preserved β-cell function was defined as FCP >200 pM or PCP >400 pM. β-Cell function that did not meet these criteria was described as residual.

RESULTS

At initial recruitment, 33.3% of patients had β-cell function failure, whereas 41.0% and 25.8% of patients had preserved or residual β-cell function, respectively. The percentage of patients who developed β-cell function failure during follow-up at 12, 24, 36, and 48 months after recruitment to the study was 55.8%, 75.6%, 86.7%, and 92.7%, respectively. Moreover, the slope of the β-cell function curve decreased over time, indicating that the pattern of its decline was non-linear and tapering. Seven percent of patients did not develop β-cell function failure within 4 years after diagnosis. Patients with lower initial FCP levels were more likely to develop β-cell function failure.

CONCLUSIONS

Chinese autoimmune T1D patients have considerable residual β-cell function at initial diagnosis, and the manner of progression of β-cell function failure is non-linear with a tapering decay rate. Furthermore, initial FCP levels may predict β-cell function failure in Chinese autoimmune T1D patients.

Associations of HbA1c with the timing of C-peptide responses during the oral glucose tolerance test at the diagnosis of type 1 diabetes

BACKGROUND

In new onset type 1 diabetes (T1D), overall C-peptide measures such as area under the curve (AUC) C-peptide and peak C-peptide are useful for estimating the extent of β-cell dysfunction, and for assessing responses to intervention therapy. However, measures of the timing of C-peptide responsiveness could have additional value.

OBJECTIVES

We assessed the contribution of the timing of C-peptide responsiveness during oral glucose tolerance tests (OGTTs) to hemoglobin A1c (HbA1c) variation at T1D diagnosis.

METHODS

We analyzed data from 85 individuals <18 years with OGTTs and HbA1c measurements at diagnosis. Overall [AUC and peak C-peptide] and timing measures [30-0 minute C-peptide (early); 60 to 120 minute C-peptide sum-30 minutes (late); 120/30 C-peptide; time to peak C-peptide] were utilized.

RESULTS

At diagnosis, the mean (±SD) age was 11.2 ± 3.3 years, body mass index (BMI)-z was 0.4 ± 1.1, 51.0% were male. The average HbA1c was 43.54 ± 8.46 mmol/mol (6.1 ± 0.8%). HbA1c correlated inversely with the AUC C-peptide (P < 0.001), peak C-peptide (P < 0.001), early and late C-peptide responses (P < 0.001 each), and 120/30 C-peptide (P < 0.001). Those with a peak C-peptide occurring at ≤60 minutes had higher HbA1c values than those with peaks later (P = 0.003). HbA1c variance was better explained with timing measures added to regression models (R²  = 11.6% with AUC C-peptide alone; R²  = 20.0% with 120/30 C-peptide added; R²  = 13.7% with peak C-peptide alone, R²  = 20.4% with timing of the peak added). Similar associations were seen between the 2-hour glucose and the C-peptide measures.

CONCLUSIONS

These findings show that the addition of timing measures of C-peptide responsiveness better explains HbA1c variation at diagnosis than standard measures alone.

Beta cell function in type 1 diabetes determined from clinical and fasting biochemical variables

AIMS/HYPOTHESIS

Beta cell function in type 1 diabetes is commonly assessed as the average plasma C-peptide concentration over 2 h following a mixed-meal test (CPAVE). Monitoring of disease progression and response to disease-modifying therapy would benefit from a simpler, more convenient and less costly measure. Therefore, we determined whether CPAVE could be reliably estimated from routine clinical variables.

METHODS

Clinical and fasting biochemical data from eight randomised therapy trials involving participants with recently diagnosed type 1 diabetes were used to develop and validate linear models to estimate CPAVE and to test their accuracy in estimating loss of beta cell function and response to immune therapy.

RESULTS

A model based on disease duration, BMI, insulin dose, HbA1c, fasting plasma C-peptide and fasting plasma glucose most accurately estimated loss of beta cell function (area under the receiver operating characteristic curve [AUROC] 0.89 [95% CI 0.87, 0.92]) and was superior to the commonly used insulin-dose-adjusted HbA1c (IDAA1c) measure (AUROC 0.72 [95% CI 0.68, 0.76]). Model-estimated CPAVE (CPEST) reliably identified treatment effects in randomised trials. CPEST, compared with CPAVE, required only a modest (up to 17%) increase in sample size for equivalent statistical power.

CONCLUSIONS/INTERPRETATION

CPEST, approximated from six variables at a single time point, accurately identifies loss of beta cell function in type 1 diabetes and is comparable to CPAVE for identifying treatment effects. CPEST could serve as a convenient and economical measure of beta cell function in the clinic and as a primary outcome measure in trials of disease-modifying therapy in type 1 diabetes.

The Effect of Age on the Progression and Severity of Type 1 Diabetes: Potential Effects on Disease Mechanisms

PURPOSE OF REVIEW

To explore the impact of age on type 1 diabetes (T1D) pathogenesis.

RECENT FINDINGS

Children progress more rapidly from autoantibody positivity to T1D and have lower C-peptide levels compared to adults. In histological analysis of post-mortem pancreata, younger age of diagnosis is associated with reduced numbers of insulin containing islets and a hyper-immune CD20^hi infiltrate. Moreover compared to adults, children exhibit decreased immune regulatory function and increased engagement and trafficking of autoreactive CD8⁺ T cells, and age-related differences in β cell vulnerability may also contribute to the more aggressive immune phenotype observed in children. To account for some of these differences, HLA and non-HLA genetic loci that influence multiple disease characteristics, including age of onset, are being increasingly characterized. The exception of T1D as an autoimmune disease more prevalent in children than adults results from a combination of immune, metabolic, and genetic factors. Age-related differences in T1D pathology have important implications for better tailoring of immunotherapies.