Saxagliptin/dapagliflozin is non-inferior to insulin glargine in terms of β-cell function in subjects with latent autoimmune diabetes in adults: A 12-month, randomized, comparator-controlled pilot study

AIM

To compare the efficacy and safety of saxagliptin/dapagliflozin and insulin glargine in people with latent autoimmune diabetes in adults (LADA).

METHODS

In this phase 2b multicentre, open-label, comparator-controlled, parallel-group, non-inferiority study, we randomly assigned 33 people with LADA who had a fasting C-peptide concentration ≥0.2 nmol/L (0.6 ng/mL) to receive 1-year daily treatment with either the combination of saxagliptin (5 mg) plus dapagliflozin (10 mg) or insulin glargine (starting dose: 10 IU), both on top of metformin. The primary outcome was the 2-h mixed meal-stimulated C-peptide area under the curve (AUC), measured 12 months after randomization. Secondary outcomes were glycated haemoglobin (HbA1c) levels, change in body mass index (BMI), and hypoglycaemic events.

RESULTS

In the modified intention-to-treat analysis, the primary outcome was similar in participants assigned to saxagliptin/dapagliflozin or to insulin glargine (median C-peptide AUC: 152.0 ng*min/mL [95% confidence interval {CI} 68.2; 357.4] vs. 122.2 ng*min/mL [95% CI 84.3; 255.8]; p for noninferiority = 0.0087). Participants randomized to saxagliptin/dapagliflozin lost more weight than those randomized to insulin glargine (median BMI change at the end of the study: -0.4 kg/m2 [95% CI -1.6; -0.3] vs. +0.4 kg/m2 [95% CI -0.3; +1.1]; p = 0.0076). No differences in HbA1c or in the number of participants experiencing hypoglycaemic events were found.

CONCLUSIONS

Saxagliptin/dapagliflozin was non-inferior to glargine in terms of β-cell function in this 12-month, small, phase 2b study, enrolling people with LADA with still viable endogenous insulin production. Weight loss was greater with saxagliptin/dapagliflozin, with no differences in glycaemic control or hypoglycaemic risk.

Safety and efficacy of teplizumab in the treatment of type 1 diabetes mellitus: An updated systematic review and meta-analysis of randomized controlled trials

AIM

To provide updated efficacy and safety information for teplizumab in the treatment of Stage 3 type 1 diabetes mellitus (T1DM).

MATERIALS AND METHODS

The PubMed, Embase and Cochrane databases were searched for randomized controlled trials (RCTs) comparing teplizumab to placebo for T1DM that reported any of the following outcomes: (1) C-peptide area under the curve (AUC); (2) glycated haemoglobin (HbA1c) levels; (3) insulin requirements; and (4) adverse events. Heterogeneity was examined with I2 statistics. p values <0.05 were taken to indicate statistical significance. The continuous endpoints were compared through the pooled mean difference (MD) and binary endpoints were assessed using risk ratios, both with 95% confidence intervals (CIs). Statistical analyses were performed using Review Manager Web software.

RESULTS

Eight RCTs with 1052 patients (754 receiving teplizumab) were included. Teplizumab significantly increased the AUC of C-peptide levels at 6 (MD 0.10 nmol/L, 95% CI 0.05, 0.16), 12 (MD 0.13 nmol/L, 95% CI 0.06, 0.20), 18 (MD 0.18 nmol/L, 95% CI 0.09, 0.27) and 24 months (MD 0.16 nmol/L, 95% CI 0.02, 0.31), significantly reduced HbA1c levels at 6 (MD -0.57%, 95% CI -1.07, -0.08) and 12 months (MD -0.31%, 95% CI -0.59, -0.02), and significantly reduced insulin requirements at 6 (MD -0.12 U/kg, 95% CI -0.16, -0.08), 12 (MD -0.11 U/kg, 95% CI -0.15, -0.07), 18 (MD -0.17 U/kg, 95% CI -0.26, -0.09) and 24 months (MD -0.11 U/kg, 95% CI -0.22, -0.01).

CONCLUSION

Teplizumab increases AUC of C-peptide levels and decreases HbA1c levels and insulin use, without raising serious adverse event risk.

Blood C-peptide concentration as a proxy marker of cardiovascular disease: An observational cross-sectional study

Background and Aims

Cardiovascular diseases (CVDs) are among the leading causes of disability and early death in sub-Saharan Africa. Most of the current blood tests for CVD diagnosis involve performing about three test profiles; often at additional cost to patients. C-peptide, a cleavage product of proinsulin, is a promising marker that has the potential to serve as a proxy marker for diagnosing CVDs in resource-poor settings.

Methodology

The study was an observational cross-sectional one and involved 127 consenting persons diagnosed with CVD and 127 individuals without CVD. The socio-demographic and clinical characteristics of participants were obtained. Blood levels of C-peptide, fasting plasma glucose (FPG), total creatinine kinase (CK), creatine kinase myocardial bound (CKMB), lactate dehydrogenase (LDH), propeptide of brain natriuretic peptide (PBNP), Troponin T, lipids, and biomarkers of kidney and liver function were analyzed using ELISA and an automated analyzer. Insulin resistance was computed using the modified homeostatic model assessment (HOMA-IR).

Results

The CVD Group had significantly higher levels of C-peptide, CK, CKMB, troponin T, PBNP, FPG, HOMA-IR, and several selected kidney, liver, and lipid parameters compared to the non-CVD Group (p < 0.05 for all). Troponin T recorded a positive correlation (r = 0.34, p < 0.001) with C-peptide among the CVD Group. The sensitivity and specificity of C-peptide in identifying CVD were 96.1% and 91.3% respectively (area under the curve = 0.938, p < 0.001).

Conclusion

C-peptide levels were higher in the CVD Group and appeared to be a valuable (high sensitivity and specificity) biomarker in detecting CVD.

Longitudinal observation of insulin secretory ability before and after the onset of immune checkpoint inhibitor-induced diabetes mellitus: A report of two cases

Immune checkpoint inhibitor-induced diabetes mellitus is a rare immune-related adverse event. This report illustrates clinical data and insulin secretory ability before and after the onset of immune checkpoint inhibitor-induced diabetes.

A quantitative measure of treatment response in recent-onset type 1 diabetes

INTRODUCTION

This paper develops a methodology and defines a measure that can be used to separate subjects that received an experimental therapy into those that benefitted from those that did not in recent-onset type 1 diabetes. Benefit means a slowing (or arresting) the decline in beta-cell function over time. The measure can be applied to comparing treatment arms from a clinical trial or to response at the individual level.

METHODS

An analysis of covariance model was fitted to the 12-month area under the curve C-peptide following a 2-hour mixed meal tolerance test from 492 individuals enrolled on five TrialNet studies of recent-onset type 1 diabetes. Significant predictors in the model were age and C-peptide at study entry. The observed minus the model-based expected C-peptide value (quantitative response, QR) is defined to reflect the effect of the therapy.

RESULTS

A comparison of the primary hypothesis test for each study included and a t test of the QR value by treatment group were comparable. The results were also confirmed for a new TrialNet study, independent of the set of studies used to derive the model. With our proposed analytical method and using QR as the end-point, we conducted simulation studies, to estimate statistical power in detecting a biomarker that expresses differential treatment effect. The QR in its continuous form provided the greatest statistical power when compared to several ways of defining responder/non-responder using various QR thresholds.

CONCLUSIONS

This paper illustrates the use of the QR, as a measure of the magnitude of treatment effect at the aggregate and subject-level. We show that the QR distribution by treatment group provides a better sense of the treatment effect than simply giving the mean estimates. Using the QR in its continuous form is shown to have higher statistical power in comparison with dichotomized categorization.

Consequences on islet and incretin hormone responses to dinner by omission of lunch in healthy men

BACKGROUND

Omission of breakfast results in higher glucose and lower insulin and incretin hormone levels after both lunch and dinner. Whether omission of lunch has a similar impact on the following meal is not known.

AIM

This study therefore explored whether omission of lunch ingestion affects glucose, islet and incretin hormones after dinner ingestion in healthy subjects.

MATERIALS & METHODS

Twelve male volunteers (mean age 22 years, BMI 22.5 kg/m2) underwent two test days in random order with standard breakfast and dinner on both days with provision or omission of standard lunch in between.

RESULTS

The results showed that throughout the 300 minutes study period, glucose, insulin, glucagon and GIP levels after dinner ingestion did not differ between the two tests. In contrast, C-peptide, and GLP-1 levels were 26%-35% higher at later time points after dinner ingestion when lunch had been omitted (P < .05).

CONCLUSION

We conclude that omission of lunch increases GLP-1 and insulin secretion and possibly also insulin clearance resulting in unchanged glucose and insulin levels after dinner ingestion.

Autocrine C-peptide protects INS1 β cells against palmitic acid-induced oxidative stress in peroxisomes by inducing catalase

AIMS

C-peptide, produced by pancreatic β cells and co-secreted in the bloodstream with insulin, has antioxidant properties in glucose- and hydrogen peroxide (H2O2)-exposed INS1 β cells. Palmitic acid, the most physiologically abundant long-chain free fatty acid in humans, is metabolized in peroxisomes of β cells accumulating H2O2 that can lead to oxidative stress. Here, we tested the hypothesis that C-peptide protects β cells from palmitic acid-induced stress by lowering peroxisomal H2O2.

MATERIALS AND METHODS

We exposed INS1 β cells to palmitic acid and C-peptide in the setting of increasing glucose concentration and tested for changes in parameters of stress and death. To study the ability of C-peptide to lower peroxisomal H2O2, we engineered an INS1 β cell line stably expressing the peroxisomal-targeted H2O2 sensor HyPer, whose fluorescence increases with cellular H2O2. An INS1 β cell line stably expressing a live-cell fluorescent catalase reporter was used to detect changes in catalase gene expression.

RESULTS

C-peptide protects INS1 β cells from the combined effect of palmitic acid and glucose by reducing peroxisomal H2O2 to baseline levels and increasing expression of catalase.

CONCLUSIONS

In conditions of glucolipotoxicity, C-peptide increases catalase expression and reduces peroxisomal oxidative stress and death of INS1 β cells. Maintenance of C-peptide secretion is a pro-survival requisite for β cells in adverse conditions. Loss of C-peptide secretion would render β cells more vulnerable to stress and death leading to secretory dysfunction and diabetes.

Serum C-peptide and osteocalcin levels in children with recently diagnosed diabetes

BACKGROUND

We explored the association of C-peptide (marker of secreted insulin), proinsulin and proinsulin ⁄C-peptide ratio (PI/C) (markers of beta-cell endoplasmic reticulum [ER] stress) with undercarboxylated (uOC) and carboxylated osteocalcin (cOC) and their ratio (uOC/cOC) in children with recently diagnosed type 1 (T1D) or type 2 diabetes (T2D), and the correlation of these variables with partial remission (PR) in children with T1D.

METHODS

Demographic and clinical data of children with new-onset diabetes (n = 68; median age = 12.2 years; 33.8% non-Hispanic White, 45.6% Hispanic/Latino, 16.2% African American and 4.4% other) were collected at diagnosis and during the first (V1), second (V2) and third clinical visits at 9.0, 32.0 and 175.7 weeks, respectively. Serum proinsulin, C-peptide, uOC and cOC values were measured 7.0 weeks after diagnosis. PR was defined as insulin dose-adjusted HbA1c (IDAA1c) ≤9.

RESULTS

In children with new-onset T1D with DKA (33.3%) or T2D (29.4%), Spearman's correlation coefficient revealed a positive association between the C-peptide levels and both uOC and uOC/cOC ratio. In T1D (n = 48), both higher serum C-peptide levels and low PI:C ratio were associated with higher BMI percentile (β = 0.02, P = .001; β = -0.01, P = .02, respectively) and older age at diagnosis (β = 0.13, P = .001; β = -0.12, P = .001, respectively). Furthermore, in children with T1D, C-peptide levels at V1 correlated with IDAA1c ≤ 9 at V1 (P = .04).

CONCLUSION

C-peptide levels are associated with a higher uOC and uOC/cOC ratio in paediatric diabetes. In new-onset T1D children, older age and higher BMI were associated with lower beta-cell stress and higher preserved function, which was predictive of PR on follow-up.

Correlation of glycated albumin but not hemoglobin A1c with endogenous insulin secretion in fulminant type 1 diabetes mellitus

Aims/Introduction:  Fulminant type 1 diabetes mellitus (FT1DM) develops as a result of very rapid and almost complete pancreatic β‐cell destruction. We hypothesized that in patients with FT1DM who have less endogenous insulin secretion, disease progression is more rapid, and thus glycated albumin (GA) levels are lower. This study was designed to prove this hypothesis.

Materials and Methods:  The present study included 42 patients with FT1DM (24 men, 18 women) in whom glycated hemoglobin (HbA_1c), GA and daily urinary C‐peptide (CPR) were measured at the time of diagnosis. Patients with complications, such as liver disease, kidney disease, anemia, or who were pregnant were excluded.

Results:  Urinary CPR (log transformed) was not correlated with HbA_1c (R = 0.168, P = 0.287), but was positively correlated with GA (R = 0.336, P = 0.030). It was weakly, but not significantly, correlated with GA/HbA_1c ratio (R = 0.281, P = 0.072). In patients with GA < 24.0%, urinary CPR was significantly lower than in patients with GA ≥ 24.0%. In addition, in patients with GA/HbA_1c ratio <3.8, urinary CPR was significantly lower than in patients with GA/HbA_1c ratio ≥ 3.8.

Conclusions:  Our findings suggest that in patients with FT1DM, GA at the time of diagnosis was correlated with endogenous insulin secretion. GA < 24.0% at the time of diagnosis is predictive for less endogenous insulin secretion in patients with FT1DM. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00050.x, 2010)

Analysis of factors influencing postprandial C-peptide levels in Japanese patients with type 2 diabetes: Comparison with C-peptide levels after glucagon load

Aims/Introduction:  Postprandial serum C‐peptide levels are readily determined in clinical practice and have a good correlation with serum C‐peptide levels after glucagon load; the measurement is often used as an index of endogenous insulin secretion. However, the factors affecting postprandial serum C‐peptide levels remain to be evaluated.

Materials and Methods:  To investigate the clinical factors affecting postprandial serum C‐peptide, 2‐h postprandial C‐peptide levels after breakfast (PPCPR) were analyzed retrospectively for comparison with glucagon‐stimulated C‐peptide (CPR‐6min) levels measured during hospital admission in 273 Japanese patients with type 2 diabetes.

Results:  Multiple regression analysis showed that years from diagnosis, body mass index (BMI) and HbA_1c were the major independent variables predicting PPCPR (R² = 0.315). HbA_1c was a major factor predicting PPCPR, but did not predict CPR‐6min. In addition, HbA_1c was negatively correlated with PPCPR (r = −0.410, P < 0.0001) and PPCPR/CPR‐6min (r = −0.313, P < 0.0001).

Conclusions:  PPCPR was correlated with common factors predicting CPR, including years from diagnosis and BMI, but also was negatively correlated with HbA_1c, a unique factor. These results show that chronic elevation of the glucose level might impair endogenous insulin secretion after meal load, but might have little effect on endogenous insulin secretion after glucagon load. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2011.00126.x, 2011)

Utility of indices using C-peptide levels for indication of insulin therapy to achieve good glycemic control in Japanese patients with type 2 diabetes

Aims/Introduction:  Type 2 diabetes is progressive in that therapy must be altered over time, which is partly as a result of the progressive loss of pancreatic β‐cell function. To elucidate the relationship between residual endogenous insulin secretion and the necessity of insulin therapy to achieve good glycemic control, indices using serum C‐peptide immunoreactivity (CPR) were analyzed in patients with type 2 diabetes.

Materials and Methods:  The data of 201 Japanese patients with type 2 diabetes who achieved the target of glycemic control during admission were analyzed retrospectively. Indices using CPR including fasting CPR (FCPR), CPR 6 min after intravenous injection of glucagon (CPR‐6 min), increment of CPR (ΔCPR), secretory unit of islet in transplantation index (SUIT) and C‐peptide index (CPI) were compared between the group requiring insulin (insulin group) and the group not requiring insulin (non‐insulin group). A receiver–operator characteristic (ROC) curve was made, and optimal cut‐off point and likelihood ratio were determined for each index.

Results:  All indices of CPR were lower in the insulin group compared with those in the non‐insulin group. Likelihood ratios at the optimal point of FCPR, CPR‐6 min, ΔCPR, SUIT, and CPI were 2.0, 2.1, 1.6, 2.3 and 2.8, respectively. Optimal cut‐off point of CPI was 1.1 ng/mg. Sensitivity and specificity at optimal point of CPI were 61 and 78%, respectively.

Conclusions:  The advantage of CPI of the indices of CPR to select insulin therapy to achieve good glycemic control was shown, but limitations of the predictive abilities of the indices using CPR should be taken into account. (J Diabetes Invest, doi: 10.1111/j.2040‐1124.2010.00096.x, 2011)

Postprandial C-peptide to glucose ratio as a predictor of β-cell function and its usefulness for staged management of type 2 diabetes

Aims/Introduction

Type 2 diabetes is characterized by progressive deterioration of β‐cell function. Recently, it was suggested that the C‐peptide‐to‐glucose ratio after oral glucose ingestion is a better predictor of β‐cell mass than that during fasting. We investigated whether postprandial C‐peptide‐to‐glucose ratio (PCGR) reflects β‐cell function, and its clinical application for management of type 2 diabetes.

Materials and Methods

We carried out a two‐step retrospective study of 919 Korean participants with type 2 diabetes. In the first step, we evaluated the correlation of PCGR level with various markers for β‐cell function in newly diagnosed and drug‐naïve patients after a mixed meal test. In the second step, participants with well‐controlled diabetes (glycated hemoglobin <7%) were divided into four groups according to treatment modality (group I: insulin, group II: sulfonylurea and/or dipeptityl peptidase IV inhibitor, group III: metformin and/or thiazolidinedione and group IV: diet and exercise group).

Results

In the first step, PCGR was significantly correlated with various insulin secretory indices. Furthermore, PCGR showed better correlation with glycemic indices than homeostatic model assessment of β‐cell function (HOMA‐β). In the second step, the PCGR value significantly increased according to the following order: group I, II, III, and IV after adjusting for age, sex, body mass index and duration of diabetes. The cut‐off values of PCGR for separating each group were 1.457, 2.870 and 3.790, respectively (P < 0.001).

Conclusions

We suggest that PCGR might be a useful marker for β‐cell function and an ancillary parameter in the choice of antidiabetic medication in type 2 diabetes.

Tolerability, effectiveness and predictive parameters for the therapeutic usefulness of exenatide in obese, Korean patients with type 2 diabetes

Aims/Introduction

We assessed the tolerability, effectiveness and predictive parameters for the therapeutic usefulness of exenatide in obese Korean participants with type 2 diabetes. We also evaluated the characteristics of participants who respond adequately to glucagon‐like peptide‐1 (GLP‐1) analog therapy in terms of glycated hemoglobin (HbA1c) level reductions and weight loss.

Materials and Methods

This prospective, observational, single‐arm (exenatide b.i.d. in combination with both metformin and sulphonylurea), open‐label study of GLP‐1 analog treatment with close monitoring of metabolic parameters and weight changes was carried out for up to 22 weeks.

Results

Of the 110 enrolled obese participants, 37 participants dropped out during the 22‐week treatment period. A total of 73 participants completed the study (median age 55.0 years, interquartile range 44.0–65.0). The median duration of diabetes was 8.0 years (interquartile range 3.5–12.5) with a mean HbA1c value of 7.6% (interquartile range 7.00–8.55). The median body mass index was 30.78 kg/m² (interquartile range 27.89–33.92). After 22 weeks, median changes from baseline for HbA1c levels and weight were −0.7% and −3.0 kg, respectively, which were significant. No severe hypoglycemic events were observed. Multivariate regression analysis showed that C‐peptide values were a significant independent predictor for a reduction in HbA1c levels (β = 0.865, P = 0.018) with exenatide BID in combination with both sulphonylurea and metformin in obese Korean participants with type 2 diabetes and insulin naïveté.

Conclusions

Clinical and laboratory parameters, such as insulin naïveté and preserved β‐cell function, should be taken into consideration as important factors in the choice of GLP‐1 analog when predicting GLP‐1 analog responsiveness. This trial was registered with the local committee at Yonsei University in Korea (4‐2011‐0032).

Postprandial serum C-peptide value is the optimal index to identify patients with non-obese type 2 diabetes who require multiple daily insulin injection: Analysis of C-peptide values before and after short-term intensive insulin therapy

Aims/Introduction

Type 2 diabetes is a progressive disease characterized by a yearly decline in insulin secretion; however, no definitive evidence exists showing the relationship between decreased insulin secretion and the need for insulin treatment. To determine the optimal insulin secretory index for identifying patients with non‐obese type 2 diabetes who require multiple daily insulin injection (MDI), we evaluated various serum C‐peptide immunoreactivity (CPR) values.

Materials and Methods

We near‐normalized blood glucose with intensive insulin therapy (IIT) over a 2‐week period in 291 patients with non‐obese type 2 diabetes, based on our treatment protocol. After improving hyperglycemia, we challenged with oral hypoglycemic agent (OHA), and according to the responsiveness to OHA, patients were classified into three therapy groups: OHA alone (n = 103), basal insulin plus OHA (basal insulin‐supported oral therapy [BOT]; n = 56) and MDI (n = 132). Glucagon‐loading CPR increment (ΔCPR), fasting CPR (FCPR), CPR 2 h after breakfast (CPR2h), the ratio of FCPR to FPG (CPI), CPI 2 h after breakfast (CPI2h) and secretory unit of islets in transplantation (SUIT) were submitted for the analyses. Receiver operating characteristic (ROC) and multiple logistic analyses for these CPR indices were carried out.

Results

Many CPR values were significantly lower in the MDI group compared with the OHA alone or BOT groups. ROC and multiple logistic analyses disclosed that post‐prandial CPR indices (CPR2h and CPI2h) were the most reliable CPR markers to identify patients requiring MDI.

Conclusions

Postprandial CPR level after breakfast is the most useful index for identifying patients with non‐obese type 2 diabetes who require MDI therapy.

Insulinemia and the risk of breast cancer and its relapse

A fairly large body of evidence has shown that insulin is a tumour-promoting agent, especially for breast cancer. High circulating and microenvironmental levels of insulin may directly increase the risk of breast cancer via the activation of cognate receptors expressed on normal and cancer cells and indirectly be associated with other known metabolic risk factors of cancer that usually are present in conjunction with the hyperinsulinic state. The focus of this review is to analyse and discuss available data in the literature on the possible causative/prognostic role of insulin resistance/hyperinsulinemia in breast cancer development and progression.