C-peptide and glucagon profiles in minority children with type 2 diabetes mellitus

Childhood Obesity, Diabetes. and Cardiovascular Disease Risk

This mini-review aims to briefly summarize the pathophysiology of childhood obesity, type 2 diabetes mellitus (T2DM), and cardiovascular disease (CVD) risk in children and adolescents. Recent data on efficacy of lifestyle interventions, medications, and metabolic surgery for obesity, T2DM, and CVD risk factors are also reviewed. We conducted a PubMed search of English-language original and review articles relevant to childhood obesity, T2DM, and CVD risk factors, and biomarkers in children with an emphasis on recent publications. Childhood obesity arises from an intricate interaction between genetic, physiologic, environmental, and socioeconomic factors. The rise in the prevalence of childhood obesity is associated with the development of comorbidities including T2DM and CVD at an early age. A multipronged approach is central to the detection, monitoring, and management of childhood obesity and associated adverse metabolic consequences.

Hyperglucagonemia in Pediatric Adiposity Associates With Cardiometabolic Risk Factors but Not Hyperglycemia

CONTEXT

In adults, hyperglucagonemia is associated with type 2 diabetes, impaired glucose tolerance, and obesity. The role of glucagon in pediatric overweight/obesity remains unclear.

OBJECTIVE

We examined whether fasting concentrations of glucagon are elevated in youth with overweight/obesity and whether this associates with cardiometabolic risk profiles.

METHODS

Analyses were based on the cross-sectional HOLBAEK study, including children and adolescents 6 to 19 years of age, with overweight/obesity from an obesity clinic group (n = 2154) and with normal weight from a population-based group (n = 1858). Fasting concentrations of plasma glucagon and cardiometabolic risk outcomes were assessed, and multiple linear and logistic regressions models were performed.

RESULTS

The obesity clinic group had higher glucagon concentrations than the population-based group (P < 0.001). Glucagon positively associated with body mass index (BMI) standard deviation score (SDS), waist, body fat %, liver fat %, alanine transaminase (ALT), high-sensitivity C-reactive protein, homeostasis model assessment of insulin resistance, insulin, C-peptide, LDL-C, triglycerides, SDS of diastolic and systolic blood pressure, and was inversely associated with fasting glucose. The inverse relationship between glucagon and glucose was attenuated in individuals with high BMI SDS and high fasting insulin. Glucagon was associated with a higher prevalence of insulin resistance, increased ALT, dyslipidemia, and hypertension, but not with hyperglycemia. Glucagon was positively associated with fasting total glucagon-like peptide-1.

CONCLUSION

Compared with normal weight peers, children and adolescents with overweight/obesity had elevated concentrations of fasting glucagon, which corresponded to worsened cardiometabolic risk outcomes, except for hyperglycemia. This suggests hyperglucagonemia in youth may precede impairments in glucose regulation.

Pathophysiology of Type 2 Diabetes in Children and Adolescents

BACKGROUND

The prevalence of type 2 diabetes (DM) in children is disturbingly increasing in parallel with the increasing childhood obesity. Better knowledge regarding the pathophysiology of type 2 DM in children is paramount to devise an effective management plan.

OBJECTIVE

Discuss the pathophysiology of type 2 DM in children and adolescents.

METHODS AND RESULTS

This is a comprehensive review of the literature on this topic. Type 2 DM in childhood is viewed as a continuum of insulin resistance (IR) which is determined by an underlying genetic predisposition, intrauterine environment, excessive food consumption, continued rapid weight gain, and poor lifestyle. Besides IR, this is compounded by multiple metabolic defects including β-cell dysfunction and inadequate insulin secretion, α-cell dysfunction, hyperglucagonemia and increased hepatic glucose production, lipotoxicity, inflammation, deficiencies in incretin production and action, and increased renal glucose reabsorption. The confluence of genetic and environmental factors underscores the complexity in disease progression.

CONCLUSION

A consistent single risk factor for type 2 DM is obesity and related IR and therefore it is essential to curtail the progression of obesity. It is important to investigate the role of stringent dietary and nutritional approaches, medications that enhance β-cell function and insulin sensitivity.

Higher glucagon-to-insulin ratio is associated with elevated glycated hemoglobin levels in type 2 diabetes patients

BACKGROUND/AIMS

The importance of α-cell dysfunction in the pathogenesis of type 2 diabetes has re-emerged recently. However, data on whether relative glucagon excess is present in clinical settings are scarce. We aimed to investigate associations between glucagon-to-insulin ratio and various metabolic parameters.

METHODS

A total of 451 patients with type 2 diabetes naïve to insulin treatment were recruited. Using glucagon-to-insulin ratio, we divided subjects into quartiles according to both fasting and postprandial glucagon-to-insulin ratios.

RESULTS

The mean age of the subjects was 58 years, with a mean body mass index of 25 kg/m2 . The patients in the highest quartile of glucagon-to-insulin ratio had higher glycated hemoglobin (HbA1c) levels. HbA1c levels were positively correlated with both fasting and postprandial glucagon-to-insulin ratios. Subjects in the highest quartile of postprandial glucagon-to-insulin ratio were more likely to exhibit uncontrolled hyperglycemia, even after adjusting for confounding factors (odds ratio, 2.730; 95% confidence interval, 1.236 to 6.028; p for trend < 0.01).

CONCLUSION

Hyperglucagonemia relative to insulin could contribute to uncontrolled hyperglycemia in type 2 diabetes patients.

Clinical and Metabolic Characteristics among Mexican Children with Different Types of Diabetes Mellitus

Background

Current classification of diabetes mellitus (DM) is based on etiology and includes type 1 (T1DM), type 2 (T2DM), gestational, and other. Clinical and pathophysiological characteristics of T1DM and T2DM in the same patient have been designated as type 1.5 DM (T1.5DM).

Objectives

The aim of this study was to classify pediatric patients with DM based on pancreatic autoimmunity and the presence or absence of overweight/obesity, and to compare the clinical, anthropometric, and biochemical characteristics between children in the different classes of DM.

Methods

A sample of 185 patients, recruited (March 2008-April 2015) as part of the Cohort of Mexican Children with DM (CMC-DM); ClinicalTrials.gov, identifier: NCT02722655. The DM classification was made considering pancreatic autoimmunity (via antibodies GAD-65, IAA, and AICA) and the presence or absence of overweight/obesity. Clinical, anthropometric and biochemical variables, grouped by type of DM were compared (Kruskal-Wallis or chi-squared test).

Results

The final analysis included 140 children; 18.57% T1ADM, 46.43% T1BDM, 12.14% T1.5DM, and 22.86% T2DM. Fasting C-Peptide (FCP), and hs-CRP levels were higher in T1.5DM and T2DM, and the greatest levels were observed in T1.5DM (p<0.001 and 0.024 respectively).

Conclusions

We clearly identified that the etiologic mechanisms of T1DM and T2DM are not mutually exclusive, and we detailed why FCP levels are not critical for the classification system of DM in children. The findings of this study suggest that T1.5DM should be considered during the classification of pediatric DM and might facilitate more tailored approaches to treatment, clinical care and follow-up.

Altered Plasma Levels of Glucagon, GLP-1 and Glicentin During OGTT in Adolescents With Obesity and Type 2 Diabetes

CONTEXT

Proglucagon-derived hormones are important for glucose metabolism, but little is known about them in pediatric obesity and type 2 diabetes mellitus (T2DM).

OBJECTIVE

Fasting and postprandial levels of proglucagon-derived peptides glucagon, GLP-1, and glicentin in adolescents with obesity across the glucose tolerance spectrum were investigated.

DESIGN

This was a cross-sectional study with plasma hormone levels quantified at fasting and during an oral glucose tolerance test (OGTT).

SETTING

This study took place in a pediatric obesity clinic at Uppsala University Hospital, Sweden.

PATIENTS AND PARTICIPANTS

Adolescents with obesity, age 10-18 years, with normal glucose tolerance (NGT, n = 23), impaired glucose tolerance (IGT, n = 19), or T2DM (n = 4) and age-matched lean adolescents (n = 19) were included.

MAIN OUTCOME MEASURES

Outcome measures were fasting and OGTT plasma levels of insulin, glucagon, active GLP-1, and glicentin.

RESULTS

Adolescents with obesity and IGT had lower fasting GLP-1 and glicentin levels than those with NGT (0.25 vs 0.53 pM, P < .05; 18.2 vs 23.6 pM, P < .01) and adolescents with obesity and T2DM had higher fasting glucagon levels (18.1 vs 10.1 pM, P < .01) than those with NGT. During OGTT, glicentin/glucagon ratios were lower in adolescents with obesity and NGT than in lean adolescents (P < .01) and even lower in IGT (P < .05) and T2DM (P < .001).

CONCLUSIONS

Obese adolescents with IGT have lowered fasting GLP-1 and glicentin levels. In T2DM, fasting glucagon levels are elevated, whereas GLP-1 and glicentin levels are maintained low. During OGTT, adolescents with obesity have more products of pancreatically than intestinally cleaved proglucagon (ie, more glucagon and less GLP-1) in the plasma. This shift becomes more pronounced when glucose tolerance deteriorates.

The changing face of diabetes in youth: lessons learned from studies of type 2 diabetes

The incidence of youth type 2 diabetes (T2D), linked with obesity and declining physical activity in high-risk populations, is increasing. Recent multicenter studies have led to a number of advances in our understanding of the epidemiology, pathophysiology, diagnosis, treatment, and complications of this disease. As in adult T2D, youth T2D is associated with insulin resistance, together with progressive deterioration in β cell function and relative insulin deficiency in the absence of diabetes-related immune markers. In contrast to adult T2D, the decline in β cell function in youth T2D is three- to fourfold faster, and therapeutic failure rates are significantly higher in youth than in adults. Whether the more aggressive nature of youth T2D is driven by genetic heterogeneity or physiology/metabolic maladaptation is yet unknown. Besides metformin, the lack of approved pharmacotherapeutic agents for youth T2D that target the pathophysiological mechanisms is a major barrier to optimal diabetes management. There is a significant need for effective therapeutic options, in addition to increased prevention, to halt the projected fourfold increase in youth T2D by 2050 and the consequences of heightened diabetes-related morbidity and mortality at younger ages.

The clinical utility of C-peptide measurement in the care of patients with diabetes

C-peptide is produced in equal amounts to insulin and is the best measure of endogenous insulin secretion in patients with diabetes. Measurement of insulin secretion using C-peptide can be helpful in clinical practice: differences in insulin secretion are fundamental to the different treatment requirements of Type 1 and Type 2 diabetes. This article reviews the use of C-peptide measurement in the clinical management of patients with diabetes, including the interpretation and choice of C-peptide test and its use to assist diabetes classification and choice of treatment. We provide recommendations for where C-peptide should be used, choice of test and interpretation of results. With the rising incidence of Type 2 diabetes in younger patients, the discovery of monogenic diabetes and development of new therapies aimed at preserving insulin secretion, the direct measurement of insulin secretion may be increasingly important. Advances in assays have made C-peptide measurement both more reliable and inexpensive. In addition, recent work has demonstrated that C-peptide is more stable in blood than previously suggested or can be reliably measured on a spot urine sample (urine C-peptide:creatinine ratio), facilitating measurement in routine clinical practice. The key current clinical role of C-peptide is to assist classification and management of insulin-treated patients. Utility is greatest after 3-5 years from diagnosis when persistence of substantial insulin secretion suggests Type 2 or monogenic diabetes. Absent C-peptide at any time confirms absolute insulin requirement and the appropriateness of Type 1 diabetes management strategies regardless of apparent aetiology.

Effects of elevated fatty acid and glucose concentrations on pancreatic islet function in vitro

AIMS/HYPOTHESIS

The aims of this study were to elucidate long-term effects of increased fatty acids and glucose concentrations on islet hormone secretion, triglyceride (TG) accumulation and fuel metabolism, and to determine the role of insulin on glucagon secretion.

METHODS

Isolated normal mouse islets were exposed to palmitate (0.6 mM) in the presence of high glucose (16.7 mM). After 48 h culture, glucagon secretion and content, insulin secretion and content, TG content and glucose oxidation were measured. The impact of etomoxir, an inhibitor of carnitine palmitoyl transferase-1, as well as of insulin, and alterations in gene expression were also investigated.

RESULTS

In the presence of palmitate, (i) high glucose caused no statistically significant suppression of glucagon while this was seen in the absence of palmitate; (ii) the insulin response to high glucose was impaired and (iii) an accumulation of TG and a decline in glucose oxidation were detected, whereas the glucagon content remained unchanged. However, etomoxir was capable of reducing glucagon secretion. Addition of exogenous insulin (10(-10)-10(-6) M) failed to restore alpha cell response to normal. Furthermore, 0.6 mM palmitate reduced the mRNA levels of acetyl-CoA carboxylase-1 and sterol regulatory element-binding protein-1c.

CONCLUSIONS/INTERPRETATION

In summary, high concentrations of palmitate and glucose cause a relative increase in glucagon secretion, a decline in insulin secretion, a loss of alpha cell sensitivity to glucose and an accumulation of TG. The inability of insulin to suppress glucagon may be because of insulin resistance of alpha cells.

Fasting c-peptide and insulin-like growth factor-binding protein-1 levels help to distinguish childhood type 1 and type 2 diabetes at diagnosis

BACKGROUND

Children with new onset diabetes (n = 175) were evaluated over 12-months. Patients were presumptively diagnosed with type 2 diabetes mellitus (T2DM) (n = 26) based on obesity, a relative with T2DM, the ability to wean from insulin, and absence of glutamic acid decarboxylase-65 (GAD-65) antibodies. We hypothesized that markers of insulinization at diagnosis, including fasting C-peptide and insulin-like growth factor-binding protein (IGFBP)-1, in addition to initial CO(2) levels and urine ketones, would help in distinguishing type 1 diabetes mellitus (T1DM) from T2DM.

RESULTS

Children with T1DM (84 male, 65 female) had a mean age of 8.7 +/- 4.3 yr and a racial background of 78% white, 19% black, and 3% other. In contrast, children with T2DM (13 female, 13 male) had a mean age of 14.2 +/- 3.1 yr with a racial background of 58% black, 27% white, and 15% other. Fasting C-peptide level was 0.38 +/- 0.37 ng/mL in T1DM vs. 2.66 +/- 2.14 ng/mL in T2DM; a C-peptide of 0.85 ng/mL had 83% sensitivity in distinguishing T1DM from T2DM. Fasting IGFBP-1 level was 38.1 +/- 39.1 ng/mL (T1DM) vs. 3.6 +/- 4.5 ng/mL (T2DM); a value of 3.6 ng/dL could distinguish the two types of diabetes with 93% sensitivity. Urinary ketones were found in 79% of children with T1DM compared with 56% of those with T2DM, and the magnitude was associated with type of diabetes. Initial CO(2) level for T1DM was 17.9 +/- 6.9 mmol/L vs. 22.7 +/- 5.7 mmol/L for T2DM; a value of 21.5 mmol/L could distinguish the two types of diabetes with 83% sensitivity.

CONCLUSIONS

In addition to obesity, family history of T2DM, and absence of GAD-65 antibodies, children with new-onset T2DM may be distinguished from those with T1DM by a combination of biochemical parameters (C-peptide, IGFBP-1, CO(2), and urine ketones).

Prevention and treatment of type 2 diabetes in youth

Parallel to the increase in obesity worldwide, there has been a rise in the prevalence of type 2 diabetes mellitus (T2DM) in children and adolescents. The etiology of T2DM in youth, similar to adults, is multifactorial including genetic and environmental factors, among them obesity, sedentary lifestyle, family history of the disease, high-risk ethnicity and insulin resistance phenotype playing major roles. Treatment of T2DM should not have a glucocentric approach; it should rather target improving glycemia, dyslipidemia, hypertension, weight management and the prevention of short- and long-term complications. Prevention strategies, especially in high-risk groups, should focus on environmental change involving participation of families, schools, the food and entertainment industries and governmental agencies. Presently, limited pharmacotherapeutic options need to be expanded both for childhood T2DM and obesity. The coming decades will prove very challenging for healthcare providers battling socioeconomic waves conducive to obesity and T2DM. Evidence-based research and clinical experience in pediatrics, possibly modeled after adult trials, need to be developed if this public health threat is to be contained.

The insulin sensitivity, glucose sensitivity, and acute insulin response to glucose load in adolescent type 2 diabetes in Taiwanese

BACKGROUND

Insulin sensitivity (SI), glucose sensitivity (SG), acute insulin response to glucose load (AIR), and obesity in adolescent type 2 diabetes patients (young diabetes, YDM) in Taiwan were studied.

METHODS

Forty patients diagnosed at <22 years of age were enrolled and divided into non-obese (NOYDM, BMI < 27 kg/m(2)) and obese groups (OBYDM BMI > 27 kg/m(2)). Adult-onset type 2 diabetes patients (ADM) >40 years old (n = 41) and nondiabetic young adults (N) (n = 23) served as controls. Fasting plasma lipids, insulin, and glucose were measured. Homeostasis model assessment was calculated to estimate insulin sensitivity and beta-cell function. A frequent-sampled intravenous glucose tolerance test was performed to evaluate SI, SG, and AIR.

RESULTS

SI and AIR were significantly lower in YDM and ADM than in N (0.92 +/- 0.13, 0.8 +/- 0.15 and 3.24 +/- 0.47 x 10(-4)/U/mL for SI; 40.3 +/- 20.3, 107.3 +/- 50.2, 1208 +/- 306.3 uU/min for AIR). SG of YDM and ADM were lower compared with N (0.014 +/- 0.00138, 0.0292 +/- 0.0058 vs 0.034 +/- 0.0086 min(-1) respectively). No difference was noted between YDM and ADM. SI and SG were not different in NOYDM and OBYDM. AIR was higher in OBYDM (83.6 +/- 34.3 vs -7.6 +/- 13.66 uU/min).

CONCLUSIONS

YDM had defects in SI, SG, and AIR compared to N, which was similar to the pathophysiology of ADM. The results imply that YDM may be either a different subtype of diabetes or the same type of diabetes as ADM, with severe defects associated with earlier age of onset. OBYDM had higher AIR than NOYDM.

Youth type 2 diabetes: insulin resistance, beta-cell failure, or both?

OBJECTIVE

This study evaluates insulin sensitivity, pancreatic beta-cell function (BCF), and the balance between the two in youth with type 2 diabetes and assesses the relationship of diabetes duration and HbA(1c) to insulin sensitivity and BCF.

RESEARCH DESIGN AND METHODS

The subjects were 14 adolescents with type 2 diabetes and 20 obese control subjects of comparable age, BMI, body composition, and puberty. Insulin sensitivity was evaluated with a 3-h hyperinsulinemic (80 mU . m(-2) . min(-1)) euglycemic clamp. First-phase insulin secretion (FPIS) and second-phase insulin secretion (SPIS) were evaluated with a 2-h hyperglycemic (12.5 mmol/l) clamp. Fasting glucose rate of appearance was determined with the use of [6,6-(2)H(2)]glucose.

RESULTS

Fasting glucose rate of appearance was higher in type 2 diabetic patients than in obese control subjects (16.5 +/- 1.1 vs. 12.3 +/- 0.5 micromol . kg(-1) . min(-1); P = 0.002). Insulin sensitivity was lower in type 2 diabetic patients than in obese control subjects (1.0 +/- 0.1 vs. 2.0 +/- 0.2 micromol . kg(-1) . min(-1) per pmol/l; P = 0.001). Fasting insulin was higher in type 2 diabetic patients than in obese control subjects (289.8 +/- 24.6 vs. 220.2 +/- 18.0 pmol/l; P = 0.007), and FPIS and SPIS were lower (FPIS: 357.6 +/- 42.0 vs. 1,365.0 +/- 111.0 pmol/l; SPIS: 652.2 +/- 88.8 vs. 1,376.4 +/- 88.8 pmol/l; P < 0.001 for both). The glucose disposition index (GDI = insulin sensitivity x FPIS) was approximately 86% lower in type 2 diabetic patients than in obese control subjects. HbA(1c) correlated with FPIS (r = -0.61, P = 0.025) with no relationship to insulin sensitivity.

CONCLUSIONS

Despite the impairment in both insulin sensitivity and BCF in youth with type 2 diabetes, the magnitude of the derangement is greater in BCF than insulin sensitivity when compared with that in obese control subjects. The inverse relationship between BCF and HbA(1c) may either reflect the impact of deteriorating BCF on glycemic control or be a manifestation of a glucotoxic phenomenon on BCF. Future studies in youth type 2 diabetes should target the natural course of beta-cell failure and means of retarding and/or preventing it.

Pathophysiology of Type 2 Diabetes Mellitus in Children and Adolescents

Type 2 diabetes mellitus was considered an exclusive disease of adulthood until the late 1970s, when reports of an increased prevalence in the pediatric age group emerged in the literature. The concerning upswing in the rate of diagnosis of type 2 diabetes mellitus in children and adolescents has continued, parallel to the increasing rates of obesity. The disease is not specific to the U.S.; it has proven to be a global problem. The current information on type 2 diabetes mellitus in children and adolescents is mostly extrapolated from studies in adults with type 2 diabetes mellitus, due to the paucity of studies conducted in youth. Obesity, family history of type 2 diabetes mellitus, minority ethnicity and race, polycystic ovary syndrome, maternal diabetes mellitus or impaired glucose tolerance during gestation, and acanthosis nigricans are the major risk factors and markers of youth-onset type 2 diabetes mellitus. The pathophysiology, which involves both an insulin secretion defect and resistance to insulin, needs further clarification in pediatric studies. Current management approaches involve lifestyle modification (nutritional and exercise) along with pharmacologic agents, such as insulin and oral antihyperglycemic medications, as indicated. A recent study on the use of metformin in childhood-onset type 2 diabetes mellitus demonstrated the drug to be effective and to have a good safety profile in this population. However, the outcomes of ongoing studies and future studies focusing on type 2 diabetes mellitus in the pediatric age group will be crucial in terms of fine-tuning management plans and setting up appropriate prevention strategies.