Autoimmunity and clinical course in children with type 1, type 2, and type 1.5 diabetes

Double diabetes-when type 1 diabetes meets type 2 diabetes: definition, pathogenesis and recognition

Currently, the differentiation between type 1 diabetes (T1D) and type 2 diabetes (T2D) is not straightforward, and the features of both types of diabetes coexist in one subject. This situation triggered the need to discriminate so-called double diabetes (DD), hybrid diabetes or type 1.5 diabetes, which is generally described as the presence of the insulin resistance characteristic of metabolic syndrome in individuals diagnosed with T1D. DD not only raises the question of proper classification of diabetes but is also associated with a significantly greater risk of developing micro- and macroangiopathic complications, which was independent of glycaemic control. When considering the global obesity pandemic and increasing incidence of T1D, the prevalence of DD may also presumably increase. Therefore, it is of the highest priority to discover the mechanisms underlying the development of DD and to identify appropriate methods to prevent or treat DD. In this article, we describe how the definition of double diabetes has changed over the years and how it is currently defined. We discuss the accuracy of including metabolic syndrome in the DD definition. We also present possible hypotheses connecting insulin resistance with T1D and propose possible methods to identify individuals with double diabetes based on indirect insulin resistance markers, which are easily assessed in everyday clinical practice. Moreover, we discuss adjuvant therapy which may be considered in double diabetic patients.

Body composition and metabolic syndrome in patients with type 1 diabetes

BACKGROUND

In recent years, the prevalence of obesity and metabolic syndrome in type 1 diabetes (T1DM) patients has gradually increased. Insulin resistance in T1DM deserves attention. It is necessary to clarify the relationship between body composition, metabolic syndrome and insulin resistance in T1DM to guide clinical treatment and intervention.

AIM

To assess body composition (BC) in T1DM patients and evaluate the relationship between BC, metabolic syndrome (MS), and insulin resistance in these indi-viduals.

METHODS

A total of 101 subjects with T1DM, aged 10 years or older, and with a disease duration of over 1 year were included. Bioelectrical impedance analysis using the Tsinghua-Tongfang BC Analyzer BCA-1B was employed to measure various BC parameters. Clinical and laboratory data were collected, and insulin resistance was calculated using the estimated glucose disposal rate (eGDR).

RESULTS

MS was diagnosed in 16/101 patients (15.84%), overweight in 16/101 patients (15.84%), obesity in 4/101 (3.96%), hypertension in 34/101 (33.66%%) and dyslipidemia in 16/101 patients (15.84%). Visceral fat index (VFI) and trunk fat mass were significantly and negatively correlated with eGDR (both P < 0.001). Female patients exhibited higher body fat percentage and visceral fat ratio compared to male patients. Binary logistic regression analysis revealed that significant factors for MS included eGDR [P = 0.017, odds ratio (OR) = 0.109], VFI (P = 0.030, OR = 3.529), and a family history of diabetes (P = 0.004, OR = 0.228). Significant factors for hypertension included eGDR (P < 0.001, OR = 0.488) and skeletal muscle mass (P = 0.003, OR = 1.111). Significant factors for dyslipidemia included trunk fat mass (P = 0.033, OR = 1.202) and eGDR (P = 0.037, OR = 0.708).

CONCLUSION

Visceral fat was found to be a superior predictor of MS compared to conventional measures such as body mass index and waist-to-hip ratio in Chinese individuals with T1DM. BC analysis, specifically identifying visceral fat (trunk fat), may play an important role in identifying the increased risk of MS in non-obese patients with T1DM.

Approach to the Patient: Youth-Onset Type 2 Diabetes

Youth-onset type 2 diabetes is a growing epidemic with a rising incidence worldwide. Although the pathogenesis and diagnosis of youth-onset type 2 diabetes are similar to adult-onset type 2 diabetes, youth-onset type 2 diabetes is unique, with greater insulin resistance, insulin hypersecretion, and faster progression of pancreatic beta cell function decline. Individuals with youth-onset type 2 diabetes also develop complications at higher rates within short periods of time compared to adults with type 2 diabetes or youth with type 1 diabetes. The highest prevalence and incidence of youth-onset type 2 diabetes in the United States is among youth from minoritized racial and ethnic groups. Risk factors include obesity, family history of type 2 diabetes, comorbid conditions and use of medications associated with insulin resistance and rapid weight gain, socioeconomic and environmental stressors, and birth history of small-for-gestational-age or pregnancy associated with gestational or pregestational diabetes. Patients with youth-onset type 2 diabetes should be treated using a multidisciplinary model with frequent clinic visits and emphasis on addressing of social and psychological barriers to care and glycemic control, as well as close monitoring for comorbidities and complications. Intensive health behavior therapy is an important component of treatment, in addition to medical management, both of which should be initiated at the diagnosis of type 2 diabetes. There are limited but growing pharmacologic treatment options, including metformin, insulin, glucagon-like peptide 1 receptor agonists, and sodium-glucose cotransporter 2 inhibitors. Although long-term outcomes are not fully known, metabolic/bariatric surgery in youth with type 2 diabetes has led to improved cardiometabolic outcomes.

A longitudinal assessment of diabetes autoantibodies in the SEARCH for diabetes in youth study

To assess changes in diabetes autoantibodies (DAs) over time in children and young adults with diabetes and determine whether observed changes were associated with demographic characteristics, clinical parameters and diabetes complications. Participants had DAs measured at baseline (10.3 ± 7.1 months after diabetes diagnosis) and at 12, 24 months and ≥5 years after the baseline measurement. At the ≥5-year follow-up, the presence of diabetes complications was assessed. We examined the associations between change in number of positive DAs and changes in individual DA status with the participants' characteristics and clinical parameters over time. Out of 4179 participants, 62% had longitudinal DA data and 51% had complications and longitudinal DA data. In participants with ≥1 baseline positive DA (n = 1699), 83.4% remained positive after 7.3 ± 2.3 years duration of diabetes. Decrease in number of positive DAs was associated with longer diabetes duration (p = 0.003 for 1 baseline positive DA; p < 0.001 for 2 baseline positive DAs) and younger age at diagnosis (p < 0.001 for 2 baseline positive DAs). No associations were found between change in number of positive DAs in participants with ≥1 baseline positive DA (n = 1391) and HbA1c, insulin dose, acute, or chronic complications after 7.7 ± 1.9 years duration of diabetes. DA status likely remains stable in the first 7 years after diabetes diagnosis. Younger age at diabetes diagnosis and longer duration were associated with less persistence of DAs. Measuring DAs after initial presentation may aid in diabetes classification but not likely in predicting the clinical course.

Latent autoimmune diabetes in youth shows greater autoimmunity than latent autoimmune diabetes in adults: Evidence from a nationwide, multicenter, cross-sectional study

AIM

To investigate the prevalence and clinical features of latent autoimmune diabetes in youth (LADY) diagnosed between 15 and 29 years old as a component of an age-related autoimmune diabetes spectrum.

RESEARCH DESIGN AND METHODS

This nationwide, multicenter, cross-sectional study continuously included 19,100 newly diagnosed diabetes patients over 15 years old across China. LADY patients were screened from 1803 subjects aged between 15 and 29 years old, with the type 2 diabetes (T2D) phenotype and positive autoantibodies against glutamic acid decarboxylase (GADA), insulinoma-associated-2 (IA-2A) or zinc transporter-8 (ZnT8A). The clinical features of LADY, including metabolic status, β-cell function and insulin resistance, were investigated and compared with those of latent autoimmune diabetes in adults (LADA) identified from 17,297 other subjects over 30 years old. The age-related characteristics of the latent autoimmune diabetes spectrum were explored.

RESULTS

A total of 135 subjects were diagnosed as LADY, accounting for 9.0% of the T2D phenotypic youth. Compared with autoantibody-negative T2D patients, LADY patients had fewer metabolic syndrome, less insulin resistance and poorer β-cell function, which were closely related to their autoantibody status (all p < 0.05). After stratifying LADA according to age, the GADA titer decreased across the LADY, "Y-LADA" (young LADA, onset age < 60 years old) and "E-LADA" (elderly LADA, onset age ≥ 60 years old) groups, while the prevalence of metabolic syndrome and level of β-cell function increased (all p < 0.05).

CONCLUSIONS

A high prevalence of LADY exists in youth with T2D phenotype. Latent autoimmune diabetes forms a continuous age-related spectrum from LADY to LADA, in which LADY shows greater autoimmunity.

Changes of insulin resistance status and development of complications in type 1 diabetes mellitus: Analysis of DCCT/EDIC study

AIM

There is no longitudinal study regarding the changes of insulin resistance (IR) status and the development of complications in type 1 diabetes (T1D). By analyzing data sets from DCCT/EDIC study, we investigated the associations of IR status changes and diabetic complications in T1D.

MATERIALS AND METHODS

Estimated glucose disposal rate (eGDR) was calculated at entry of DCCT and in EDIC year 12 (average 18.5 years later) to represent IR. The participants (n = 957) were divided into four groups based on IR changes from baseline: RR group (stayed resistant; n = 49), RS group (became sensitive; n = 42), SR group (became resistant; n = 197), and SS group (stayed sensitive; n = 669). The association of diabetic complications were analyzed by using multivariable logistic regression models.

RESULTS

The improved IR decreased the risk of peripheral neuropathy, whereas the deteriorated IR increased the risk of diabetic complications including hypertension, peripheral artery disease, coronary artery calcification, retinopathy, albuminuria, peripheral neuropathy, and cardiac autonomic neuropathy (P < 0.05). Moreover, RR group (HR = 3.59, 95% CI (2.05-6.32)), RS group (HR = 2.27, 95% CI (1.11-4.64)) and SR group (HR = 1.90, 95% CI (1.24-2.92)) had higher risk of cardiovascular events compared to SS group (P < 0.05).

CONCLUSIONS

This study highlights the importance of IR changes represented by eGDR in the development of diabetic complications. Patients with T1D and IR may require intensive therapy.

Clinical Pharmacokinetics and Pharmacodynamics of Antihyperglycemic Medications in Children and Adolescents with Type 2 Diabetes Mellitus

The incidence of type 2 diabetes mellitus (T2DM) among children and adolescents has been rising. This condition is associated with obesity, and it's prevalence is higher among minority or female youth. Lifestyle modification including diet and exercise is only successful in a small proportion of patients; therefore, pharmacotherapy approaches are needed to treat T2DM among youth. Currently, in the USA, only metformin and insulin are approved for the treatment of T2DM in children. However, several antihyperglycemic agents including exenatide, glimepiride, glyburide, liraglutide, pioglitazone, and rosiglitazone are also used off-label in this population. Moreover, a number of clinical trials are ongoing that are aimed at addressing the safety and efficacy of newer antihyperglycemic agents in this population. Little is known about the safety, efficacy, or pharmacokinetics of antihyperglycemic agents in children or adolescents. Our ability to predict the pharmacokinetics of these agents in youth is hampered first by the lack of information about the expression and activity of drug-metabolizing enzymes and transporters in this population and second by the presence of comorbid conditions such as obesity and fatty liver disease. This article reviews the prevalence of obesity and T2DM in children and adolescents (youth). We then summarize published studies on safety and effectiveness of antihyperglycemic medications in youth. Drug disposition may be affected by age or puberty and thus the expression and activity of different pathways for drug metabolism and xenobiotic transporters are compared between youth and adults followed by a summary of pharmacokinetics studies of antihyperglycemic agents currently used in this population.

Metabolic risk profiles in diabetes stratified according to age at onset, islet autoimmunity and fasting C-peptide

OBJECTIVE

Islet autoimmunity, age at onset and time to insulin treatment are often used to define subgroups of diabetes. However, the latter criterion is not clinical useful. Here, we examined whether an unbiased stratification of diabetes according to age at onset, fasting C-peptide and GAD autoantibodies (GADab) defines groups with differences in glycaemic control and markers of cardiometabolic risk.

DESIGN AND METHODS

A cohort of 4374 adults with relatively newly diagnosed diabetes referred to a Danish hospital during 1997-2012 was stratified according to age at onset above or below 30 years, fasting C-peptide above or below 300 pmol/l (CPEP_high or CPEP_low), and presence or absence of GADab (GAD_pos or GAD_neg). HbA_1c, BMI, blood pressure (BP), lipid profile, alanine aminotransferase (ALT) and creatinine were evaluated.

RESULTS

GADab were present in 13% of the cohort. Age at onset was not associated with major differences between groups. Patients with insulin deficient diabetes (CPEP_low; n = 503) had higher HbA_1c but otherwise lower cardiometabolic risk (lower BMI, BP, LDL, triacylglycerol, and ALT, and higher HDL) than both patients with latent autoimmune diabetes of adults (LADA defined as GAD_posCPEP_high; n = 327) and patients with type 2 diabetes (GAD_negCPEP_high; n = 3544). Patients with LADA defined an intermediate group with higher HbA_1c but otherwise lower cardiometabolic risk than patients with type 2 diabetes.

CONCLUSIONS

Our results demonstrate that fasting C-peptide and GADab status, but not age at onset, define groups of patients with diabetes with clinically relevant differences in glycaemic control and cardiometabolic risk.

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.

Utility of diabetes-associated autoantibodies for classification of new onset diabetes in children and adolescents

OBJECTIVE

To determine whether measuring diabetes-associated autoantibodies (DAA) in pediatric new onset diabetes (NODM) can be restricted to patients with equivocal diabetes type.

RESEARCH DESIGN AND METHODS

Retrospective analysis of all patients with NODM admitted to Boston Children's Hospital from 1 October 2007 to 1 July 2013 who had measurement of DAA [glutamic acid decarboxylase, insulin, insulinoma-associated antigen 2 (IA-2)]. Data collection included initial diagnosis of diabetes type before DAA results and at follow-up. We used logistic regression to predict type 1 diabetes (T1D) and developed a clinical score to classify diabetes type.

RESULTS

Of 1089 patients (45.4% female, 76.7% White, age 10.6 ± 4.5 yr), initial diagnosis was 1021 (93.8%) T1D, 42 (3.9%) type 2 diabetes (T2D), and 26 (2.4%) other. Of 993 patients with clinical T1D, 78 (7.9%) were DAA-, and of 42 patients with clinical T2D, 12 (28.6%) were DAA+. Type of diabetes was reclassified at follow-up in less than 6% of patients. Data from a subset of 736 patients were used to develop a scoring system to predict T1D. Using weight z-score, age, and race, the scoring system had 91.7% sensitivity, 82% specificity, and a positive predictive value of 98.6%, and suggested DAA measurement was unnecessary in 85.3% of patients. Findings were similar in a validation cohort of 234 patients.

CONCLUSIONS

Application of a simple scoring system may reduce to ∼15% the number of DAA measurements needed to classify diabetes type, resulting in substantial cost savings. Clinical judgment should guide the decision to measure DAA.

Insulin resistance in type 1 diabetes mellitus

For long the presence of insulin resistance in type 1 diabetes has been questioned. Detailed metabolic analyses revealed 12%-61% and up to 20% lower whole-body (skeletal muscle) and hepatic insulin sensitivity in type 1 diabetes, depending on the population studied. Type 1 diabetes patients feature impaired muscle adenosine triphosphate (ATP) synthesis and enhanced oxidative stress, predominantly relating to hyperglycemia. They may also exhibit abnormal fasting and postprandial glycogen metabolism in liver, while the role of hepatic energy metabolism for insulin resistance remains uncertain. Recent rodent studies point to tissue-specific differences in the mechanisms underlying insulin resistance. In non-obese diabetic mice, increased lipid availability contributes to muscle insulin resistance via diacylglycerol/protein kinase C isoforms. Furthermore, humans with type 1 diabetes respond to lifestyle modifications or metformin by 20%-60% increased whole-body insulin sensitivity, likely through improvement in both glycemic control and oxidative phosphorylation. Intensive insulin treatment and islet transplantation also increase but fail to completely restore whole-body and hepatic insulin sensitivity. In conclusion, insulin resistance is a feature of type 1 diabetes, but more controlled trials are needed to address its contribution to disease progression, which might help to optimize treatment and reduce comorbidities.

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.

Association of HLA class II markers with autoantibody-negative ketosis-prone atypical diabetes compared to type 2 diabetes in a population of sub-Saharan African patients

AIM

We investigated the association of HLA DRB1 and DQB1 alleles, haplotypes and genotypes with unprovoked antibody-negative ketosis-prone atypical diabetes (A(-) KPD) in comparison to type 2 diabetes (T2D).

METHODS

A(-) KPD and T2D sub-Saharan African patients aged 19-63 years were consecutively recruited. Patients positive for cytoplasmic islet cell, insulin, glutamic acid decarboxylase or islet antigen-2 autoantibodies were excluded. Odds ratios were obtained via logistic regression after considering alleles with a minimum frequency of 5% in the study population. Bonferroni correction was used in the case of multiple comparisons.

RESULTS

Among the 130 participants, 35 (27%) were women and 57 (44%) were A(-) KPD. DRB1 and DQB1 allele frequencies were similar for both A(-) KPD and T2D patients; they did not confer any substantial risk even after considering type 1 diabetes susceptibility and resistance alleles. We found no association between A(-) KPD and the derived DRB1*07-DQB1*02:02 (OR: 0.55 [95%CI: 0.17-1.85], P=0.336); DRB1*11-DQB1*03:01 (OR: 2.42 [95%CI: 0.79-7.42], P=0.123); DRB1*15-DQB1*06:02 (OR: 0.87 [95%CI: 0.39-1.95], P=0.731) and DRB1*03:01-DQB1*02:01 (OR: 1.48 [95%CI: 0.55-3.96], P=0.437) haplotypes. Overall, we did not find any evidence of susceptibility to ketosis associated with DRB1 and DQB1 genotypes (all P>0.05) in A(-) KPD compared to T2D. Similar results were obtained after adjusting the analysis for age and sex.

CONCLUSION

Factors other than DRB1 and DQB1 genotype could explain the propensity to ketosis in A(-) KPD. These results need to be confirmed in a larger population with the perspective of improving the classification and understanding of the pathophysiology of A(-) KPD.

Mortality by race among low-income adults with early-onset insulin-treated diabetes

OBJECTIVE

To determine if long-term mortality rates in early-onset insulin-treated diabetes differ by race among adults of similar socioeconomic status.

RESEARCH DESIGN AND METHODS

A total of 391 (299 African Americans, 92 whites) mostly low-income adults 40-79 years of age with insulin-treated diabetes diagnosed before 30 years of age were recruited from community health centers in the southeast U.S. Cox models were used to estimate hazard ratios (HRs) of all-cause mortality among African Americans compared with whites. Additionally, standardized mortality ratios (SMRs) were used to compare the mortality experience of the individuals with diabetes with both national and general community health center sex- and race-specific population norms.

RESULTS

Mean age at diabetes diagnosis and cohort entry, respectively, was 21 and 50 years in African Americans and 19 and 51 years in whites. During an average of 6.7 years of follow-up, 29% of African Americans and 35% of whites died. In multivariable analysis, no significant mortality difference was observed among African Americans compared with whites (HR 0.83 [95% CI 0.53-1.30]; P=0.51). Compared with the race-specific U.S. general population, SMRs for those with diabetes were 5.7 in African Americans and 11.7 in whites. However, when compared with the same source population (i.e., the community health center population), SMRs were 3.5 and 3.7 in African Americans and whites, respectively.

CONCLUSIONS

Elevated mortality persists in men and women with long duration of early-onset insulin-treated diabetes, but given survival to 40 years of age and similarly low economic status and access to health care, our data do not suggest a racial disparity in mortality.

Use of the estimated glucose disposal rate as a measure of insulin resistance in an urban multiethnic population with type 1 diabetes

OBJECTIVE

Insulin resistance has been described in type 1 diabetes mellitus, is related to risk of vascular complications, and may be more common in certain ethnic groups. Estimated glucose disposal rate (eGDR) is a validated clinical tool for estimating insulin sensitivity in type 1 diabetes. Because previous reports of eGDR in adults with type 1 diabetes have included few ethnic minorities, this study explored interethnic differences in eGDR and the relationship of eGDR with diabetic vascular complications.

RESEARCH DESIGN AND METHODS

We conducted a cross-sectional study using a sample that included 207 white, black, or Hispanic adults with prior clinical diagnosis of type 1 diabetes who were receiving care at an urban academic medical center. eGDR (milligrams per kilogram per minute) was calculated using HbA1c, waist circumference, and hypertensive status. Race/ethnicity was self-reported. Multivariable logistic regression models were used to estimate odds ratios (ORs) and 95% CIs of association of eGDR with diabetes complications (cardiovascular disease, retinopathy, albuminuria, and chronic kidney disease above stage 3).

RESULTS

Forty-two percent of the participants were women, and mean age was 45 ± 15 years; 34% were white, 32% were Hispanic, and 34% were black. Ethnicity was significantly associated with eGDR; blacks had significantly lower eGDR (5.66 ± 2.34) than Hispanics (6.70 ± 2.29) and whites (7.20 ± 2.03) (P < 0.001). Patients with the lowest eGDR compared with the highest had a significantly greater risk of any diabetes complication (OR 3.1 [95% CI 1.2-8.1]) compared with the least insulin-resistant patients.

CONCLUSIONS

In an urban clinic population of patients with type 1 diabetes, blacks were significantly less insulin sensitive than whites or Hispanics, and lower eGDR was associated with diabetes complications. Further study is needed to determine whether using eGDR to target interventions can improve outcomes.

Indices of insulin secretion during a liquid mixed-meal test in obese youth with diabetes

OBJECTIVE

To compare indices of insulin secretion, insulin sensitivity (IS), and oral disposition index (oDI) during the liquid mixed-meal test in obese youth with clinically diagnosed type 2 diabetes mellitus (T2DM) and negative autoantibodies (Ab(-)) versus those with T2DM and positive autoantibodies (Ab(+)) to examine whether differences in β-cell function can be detected between the 2 groups.

STUDY DESIGN

Twenty-seven youth with Ab(-) and 15 youth with Ab(+) clinically diagnosed T2DM underwent a mixed-meal test (Boost; 55% carbohydrate, 25% protein, and 20% fat). Fasting and mixed-meal-derived insulin and C-peptide indices of IS, secretion (30-minute insulinogenic [ΔI(30)/ΔG(30)] and C-peptide [ΔC(30)/ΔG(30)]), and oDI were calculated.

RESULTS

Indices of insulin secretion were ~40%-50% lower in patients with Ab(+) T2DM compared with those with Ab(-) T2DM. After controlling for body mass index, ΔI(30)/ΔG(30), ΔC(30)/ΔG(30), C-peptide area under the curve (AUC)/glucose AUC, and insulin AUC/glucose AUC were significantly (P < .05) lower in the Ab(+) group compared with the Ab(-) group. Sensitivity indices were significantly higher in the Ab(+) group. The oDI, 1/fasting insulin × ΔI(30)/ΔG(30) (0.04 ± 0.02 vs 0.12 ± 0.02 mg/dL(-1); P = .005), and 1/fasting C-peptide × ΔC(30)/ΔG(30) (0.02 ± 0.009 vs 0.05 ± 0.006 mg/dL(-1); P = .018) were lower in the Ab(+) group. Receiver operating characteristic curve analyses revealed that fasting C-peptide <3.2 ng/mL had 87% sensitivity and 74% specificity and ΔC(30)/ΔG(30) <0.075 ng/mL per mg/dL had 93% sensitivity and 80% specificity for identifying youth with Ab(+) T2DM.

CONCLUSION

During a liquid mixed-meal test, indices of β-cell function were lower and IS was higher in patients with Ab(+) T2DM versus those with Ab(-) T2DM, with high sensitivity and specificity for fasting and stimulated C-peptide as markers of Ab(+) status. Indices of insulin secretion during this standardized mixed-meal test could be used to assess β-cell function in therapeutic trials of β-cell restoration in youth with T2DM.

Bone marrow stem cell as a potential treatment for diabetes

Diabetes mellitus (DM) is a group of metabolic diseases in which a person has high blood glucose levels resulting from defects in insulin secretion and insulin action. The chronic hyperglycemia damages the eyes, kidneys, nerves, heart, and blood vessels. Curative therapies mainly include diet, insulin, and oral hypoglycemic agents. However, these therapies fail to maintain blood glucose levels in the normal range all the time. Although pancreas or islet-cell transplantation achieves better glucose control, a major obstacle is the shortage of donor organs. Recently, research has focused on stem cells which can be classified into embryonic stem cells (ESCs) and tissue stem cells (TSCs) to generate functional β cells. TSCs include the bone-marrow-, liver-, and pancreas-derived stem cells. In this review, we focus on treatment using bone marrow stem cells for type 1 and 2 DM.

Obesity is associated with activated and insulin resistant immune cells

BACKGROUND

Obesity and type 2 diabetes mellitus are characterized by insulin resistance and 'low-grade inflammation'; however, the pathophysiological link is poorly understood. To determine the relative contribution of obesity and insulin resistance to systemic 'inflammation', this study comprehensively characterized circulating immune cells in different grades of obesity.

METHODS

Immune cell phenotypes and activation status were analysed by flow cytometry cross-sectionally in morbidly obese (n = 16, body mass index (BMI) 42.2 ± 5.4 kg/m2), overweight (n = 13, BMI 27.4 ± 1.6 kg/m2) and normal weight (n = 12, BMI 22.5 ± 1.9 kg/m2) subjects.

RESULTS

Obese, but not overweight subjects, had increased activation marker expression on neutrophils, monocytes, T-lymphocytes and polarization of T helper cells towards a pro-inflammatory type 1-phenotype (Th1). Th1 numbers correlated positively with the degree of insulin resistance (homeostasis model assessment, p < 0.05). Lymphocytes from obese subjects showed reduced insulin-stimulated AKT-phosphorylation in vitro. Supra-physiological insulin concentrations did not affect T-cell differentiation, which under normal circumstances would promote an anti-inflammatory T helper type 2-phenotype.

CONCLUSIONS

These results show that morbid obesity is characterized by circulating immune cells that are activated and insulin resistant, with the T-cell balance polarized towards a pro-inflammatory Th1 phenotype. The loss of insulin-induced suppression of inflammatory phenotypes in circulating immune cells could contribute to the systemic and adipose tissue inflammation found in morbid obesity.

Levels of C-peptide, body mass index and age, and their usefulness in classification of diabetes in relation to autoimmunity, in adults with newly diagnosed diabetes in Kronoberg, Sweden

OBJECTIVE

C-peptide is a main outcome measure in treatment trials of diabetes. C-peptide also has a role in the classification of diabetes, which is often difficult in adults and this is also increasingly recognised in adolescents and elders.

AIM

We aimed to describe the levels of C-peptide in relation to age and body mass index (BMI) in a large population-based cohort of adults with newly diagnosed diabetes and compare the capabilities of C-peptide, age and BMI to discriminate between autoimmune and non-autoimmune diabetes.

SUBJECTS AND METHODS

Blood samples from 1180 patients were analysed regarding islet cell antibody, glutamic acid decarboxylase antibody and fasting C-peptide (FCP). Receiver operating characteristics (ROC) curves were analysed to check the ability of age, BMI and C-peptide to discriminate between autoantibody-positive (Ab(+)) and -negative (Ab(-)) diabetes.

RESULTS

Mean FCP was 0.73±0.5 (range 0.13-1.80) nmol/l in the Ab(+) and 1.42±0.9 (range 0.13-8.30) nmol/l in the Ab(-). FCP was 0.02 nmol/l higher per year increase in age at diagnosis of diabetes. Mean BMI was 26.0±4.8 (range 18.0-39.0) kg/m(2) in the Ab(+) and 28.9±5.3 (range 15.5-62.6) kg/m(2) in the Ab(-). FCP increased with age also within each BMI group. The highest area under the curve (AUC) in the ROC analysis was found for C-peptide, followed by age and BMI (0.78, 0.68 and 0.66 respectively).

CONCLUSIONS

At diagnosis of diabetes, C-peptide was superior to age and BMI in discriminating between autoimmune and non-autoimmune diabetes. C-peptide increased significantly with BMI and age, latter also within each BMI group. Most of the adults had normal or high levels of C-peptide at presentation of diabetes among the autoimmune patients.

Mortality experience of a low-income population with young-onset diabetes

OBJECTIVE

In young-onset diabetes, insulin therapy status is a rough marker of diabetes type. We describe the mortality experience of a low-income, predominantly minority population with diabetes diagnosed before age 30 years, stratified by insulin therapy.

RESEARCH DESIGN AND METHODS

A total of 1,098 adults aged 40-79 years (median 49) diagnosed with diabetes before age 30 years and 49,914 without diabetes were recruited from community health centers. Individuals with diabetes were categorized by insulin therapy at baseline: group A, insulin therapy only; group B, insulin therapy and an oral hypoglycemic agent; and group C, no insulin therapy. Cox models were used to compute hazard ratios (HRs) and 95% CI for cause-specific mortality based on both underlying and contributing causes of death from death certificates.

RESULTS

During follow-up (mean 3.9 years), 15.0, 12.5, and 7.3% of groups A, B, and C, respectively, and 4.6% without diabetes died. Compared with individuals without diabetes, HRs (CI) for all-cause mortality were 4.3 (3.4-5.6), 4.2 (2.8-6.3), and 2.0 (1.4-2.8) in groups A, B, and C, respectively. The leading cause of death was renal failure (end-stage renal disease [ESRD]) in group A, ESRD and coronary artery disease (CAD) in group B, and CAD in group C and individuals without diabetes. HRs for these conditions were at least twice as high as the HRs for all-cause mortality, reaching 17.3 (10.2-29.3), 17.9 (8.3-38.7), and 5.1 (2.3-11.7) in groups A, B, and C, respectively, for ESRD.

CONCLUSIONS

Excess mortality persists among people with young-onset diabetes of long duration, with ESRD and CAD as the leading contributors to mortality.

Type 2 diabetes in childhood: clinical characteristics and role of β-cell autoimmunity

The global obesity epidemic has led to dramatic increases in the incidence and prevalence of type 2 diabetes mellitus (T2DM) among youth worldwide. In today's clinical practice it has become increasingly difficult to distinguish type 1 diabetes mellitus (T1DM) from T2DM as many children with T1DM are overweight at diagnosis. Numerous recent publications note a significant proportion of physician-diagnosed T2DM youth with evidence of pancreatic autoimmunity, exemplifying the challenges in distinguishing between T1DM and T2DM. The clinical implications of the phenomenon of antibody positivity in phenotypic T2DM youth, also referred to as "type 1.5 diabetes" (T1.5 DM), "double diabetes," "latent autoimmune diabetes in youth" (LADY), and "hybrid diabetes," are unclear at present. Current and future work should determine if the presence of autoantibodies in phenotypic T2DM youth/children affects clinical course; this will facilitate the development of optimal treatment strategies.

Successful modulation of type 2 diabetes in db/db mice with intra-bone marrow--bone marrow transplantation plus concurrent thymic transplantation

There is increasing evidence that both autoimmune and autoinflammatory mechanisms are involved in the development of not only type 1 diabetes mellitus (T1 DM), but also type 2 diabetes mellitus (T2 DM). Our laboratory has focused on this concept, and in earlier efforts replaced the bone marrow cells (BMCs) of leptin receptor-deficient (db/db) mice, an animal model of T2DM, with those of normal C57BL/6 (B6) mice by IBM-BMT. However, the outcome was poor due to incomplete recovery of T cell function. Therefore, we hypothesized that intra-bone marrow-bone marrow transplantation plus thymus transplantation (IBM-BMT + TT) could be used to treat T2 DM by normalizing the T cell imbalance. Hence we addressed this issue by using such dual transplantation and demonstrate herein that seven weeks later, recipient db/db mice manifested improved body weight, reduced levels of blood glucose, and a reduction of plasma IL-6 and IL-1β. More importantly, this treatment regimen showed normal CD4/CD8 ratios, and increased plasma adiponectin levels, insulin sensitivity, and the number of insulin-producing cells. Furthermore, the expression of pancreatic pAKT, pLKB1, pAMPK and HO-1 was increased in the mice treated with IBM-BMT + TT. Our data show that IBM-BMT + TT treatment normalizes T cell subsets, cytokine imbalance and insulin sensitivity in the db/db mouse, suggesting that IBM-BMT + TT is a viable therapeutic option in the treatment of T2 DM.

The presence of GAD and IA-2 antibodies in youth with a type 2 diabetes phenotype: results from the TODAY study

OBJECTIVE

To determine the frequency of islet cell autoimmunity in youth clinically diagnosed with type 2 diabetes and describe associated clinical and laboratory findings.

RESEARCH DESIGN AND METHODS

Children (10-17 years) diagnosed with type 2 diabetes were screened for participation in the Treatment Options for Type 2 Diabetes in Adolescents and Youth (TODAY) study. Measurements included GAD-65 and insulinoma-associated protein 2 autoantibodies using the new National Institute of Diabetes and Digestive and Kidney Diseases/National Institutes of Health (NIDDK/NIH) standardized assays, a physical examination, and fasting lipid, C-peptide, and A1C determinations.

RESULTS

Of the 1,206 subjects screened and considered clinically to have type 2 diabetes, 118 (9.8%) were antibody positive; of these, 71 (5.9%) were positive for a single antibody, and 47 were positive (3.9%) for both antibodies. Diabetes autoantibody (DAA) positivity was significantly associated with race (P < 0.0001), with positive subjects more likely to be white (40.7 vs. 19%) (P < 0.0001) and male (51.7 vs. 35.7%) (P = 0.0007). BMI, BMI z score, C-peptide, A1C, triglycerides, HDL cholesterol, and blood pressure were significantly different by antibody status. The antibody-positive subjects were less likely to display characteristics clinically associated with type 2 diabetes and a metabolic syndrome phenotype, although the range for BMI z score, blood pressure, fasting C-peptide, and serum lipids overlapped between antibody-positive and antibody-negative subjects.

CONCLUSIONS

Obese youth with a clinical diagnosis of type 2 diabetes may have evidence of islet autoimmunity contributing to insulin deficiency. As a group, patients with DAA have clinical characteristics significantly different from those without DAA. However, without islet autoantibody analysis, these characteristics cannot reliably distinguish between obese young individuals with type 2 diabetes and those with autoimmune diabetes.

The accelerator hypothesis: a review of the evidence for insulin resistance as the basis for type I as well as type II diabetes

Although some 40 years have passed since type I diabetes was first defined, its cause remains unknown. The autoimmunity paradigm of immune dysregulation has not offered an explanation for its rising incidence, nor means of preventing it, and there is arguably good reason to consider alternatives. The accelerator hypothesis is a singular, unifying concept that argues that type I and type II diabetes are the same disorder of insulin resistance, set against different genetic backgrounds. The hypothesis does not deny the role of autoimmuniy, only its primacy in the process. It distinguishes type I and type II diabetes only by tempo, the faster tempo reflecting the more susceptible genotype and (inevitably) earlier presentation. Insulin resistance is closely related to the rise in overweight and obesity, a trend that the hypothesis deems central to the rising incidence of all diabetes in the developed and developing world. Rather than overlap between the two types of diabetes, the accelerator hypothesis envisages overlay-each a subset of the general population differing from each other only by genotype. Indeed, it views type I and type II diabetes as a continuum, where the infinitely variable interaction between insulin resistance and genetic response determines the age at which beta-cell loss becomes critical. Adult diabetes is not viewed as an entity, but rather as diabetes presenting in adulthood. Childhood diabetes, similarly, is diabetes presenting in childhood. The increasing incidence of both is primarily the result of lifestyle change and the rise in body weight that has resulted.

Pathophysiology of type 2 diabetes mellitus in youth: the evolving chameleon

Type 2 diabetes mellitus (T2DM) in children and adolescents is an important Public Health problem against the backdrop of the epidemic of childhood obesity. The clinical presentation of T2DM in youth is heterogeneous from minimal symptomatology to diabetic ketoacidosis. The increasing rates of youth T2DM have paralleled the escalating rates of obesity, which is the major risk factor impacting insulin sensitivity. Additional risk factors include minority race, family history of diabetes mellitus, maternal diabetes during pregnancy, pubertal age group and conditions associated with insulin resistance (IR) - such as polycystic ovary syndrome (PCOS). The pathophysiology of T2DM has been studied extensively in adults, and it is widely accepted that IR together with beta-cell failure are necessary for the development of clinical diabetes mellitus in adulthood. However, pathophysiologic studies in youth are limited and in some cases conflicting. Similar to adults, IR is a prerequisite, but beta-cell failure is necessary for progression from normal glucose tolerance to prediabetes and frank diabetes in youth. Even though rates of T2DM in youth are increasing, the overall prevalence remains low if compared with type 1 diabetes mellitus (T1DM). However, as youth with T1DM are becoming obese, the clinical distinction between T2DM and obese T1DM has become difficult, because of the overlapping clinical picture with evidence of islet cell autoimmunity in a significant proportion of clinically diagnosed youth with T2DM. The latter are most likely obese children with autoimmune T1DM who carry a misdiagnosis of T2DM. Further research is needed to probe the pathophysiological, immunological, and metabolic differences between these two groups in the hopes of assigning appropriate therapeutic regimens. These challenges combined with the evolving picture of youth T2DM and its future complications provide unending opportunities for acquisition of new knowledge in the field of childhood diabetes.

Phenotypic type 2 diabetes in obese youth: insulin sensitivity and secretion in islet cell antibody-negative versus -positive patients

OBJECTIVE

Some obese youth with a clinical diagnosis of type 2 diabetes have evidence of islet cell autoimmunity with positive autoantibodies. In this study, we investigated the differences in insulin sensitivity and secretion between autoantibody-negative (Ab-) and -positive (Ab+) youth with clinically diagnosed type 2 diabetes in comparison with control subjects.

RESEARCH DESIGN AND METHODS

Sixteen Ab- and 26 Ab+ clinically diagnosed type 2 diabetic patients and 39 obese control youth underwent evaluation of insulin sensitivity (3-h hyperinsulinemic-euglycemic clamp), substrate oxidation (indirect calorimetry), first- and second-phase insulin secretion (2-h hyperglycemic clamp), body composition and abdominal adiposity (dual energy X-ray absorptiometry and computed tomography scan, respectively), and glucose disposition index (first-phase insulin secretion x insulin sensitivity).

RESULTS

Insulin-stimulated total, oxidative, and nonoxidative glucose disposal, and suppression of fat oxidation during hyperinsulinemia were significantly lower in Ab- compared with Ab+ clinically diagnosed type 2 diabetic and control subjects with no difference between the latter two. First- and second-phase insulin secretion and C-peptide were lower in Ab+ compared with Ab- type 2 diabetes. Glucose disposition index was not different between the Ab- and Ab+ clinically diagnosed type 2 diabetic patients, but both were significantly lower than that in control subjects. Systolic blood pressure and alanine aminotransferase were higher in Ab- versus Ab+ clinically diagnosed type 2 diabetic patients, whereas the frequency of ketonuria at diagnosis was higher in Ab+ versus Ab- patients.

CONCLUSIONS

Islet-cell Ab- clinically diagnosed type 2 diabetic youth are characterized by severe insulin resistance and relative insulin deficiency, whereas Ab+ youth have severe insulin deficiency and beta-cell failure. The former group has additional features of insulin resistance. These important metabolic differences could influence the natural history of hyperglycemia, insulin dependence, and clinical outcomes in these youth.

New-onset diabetes in an obese adolescent: diagnostic dilemmas

BACKGROUND

A 14-year-old, obese, African American boy presented to his pediatrician with polyuria, polydipsia, and a significant unintentional weight loss. He was dehydrated, with high levels of blood sugar and urinary ketones. He had no history of previous illnesses and was not taking any medications. He had a family history of type 2 diabetes mellitus.

INVESTIGATIONS

Physical examination included assessing stigmata of insulin resistance, and measuring blood pressure, pulse, and BMI. Blood samples were obtained for measurement of venous blood pH, bicarbonate, serum glucose, electrolytes, HbA(1C), aminotransferases and lipids. Urine was sampled for measurement of ketones. Subsequently, measurements of fasting C-peptide and immunoassays for insulin autoantibodies (IAA), islet-cell autoantibodies (ICA-512) and glutamic acid decarboxylase autoantibodies (GAD-65) were performed.

DIAGNOSIS

New-onset diabetes mellitus with diabetic ketoacidosis, initially diagnosed as type 2 diabetes mellitus, but later determined as type 1 diabetes mellitus.

MANAGEMENT

After treatment of diabetic ketoacidosis with hydration and insulin infusion, the patient was discharged on subcutaneous insulin. He was diagnosed with type 2 diabetes mellitus and was transferred to oral insulin-sensitizing agents. He re-presented 18 months later with an insulin requirement during an asthma exacerbation treated with steroids. Due to the worsening of his diabetic symptoms, the patient was tested for islet autoantibodies and was found to be positive for GAD-65 and IAA, that is, diagnostic of type 1 diabetes mellitus. He has continued to require subcutaneous insulin.

Diabetes: 1 and 2, or one and the same? Progress with the accelerator hypothesis

The accelerator hypothesis was published in 2001, and proposes that that type 1 and type 2 diabetes are the same disorder of insulin resistance set against different genetic backgrounds. The different genes modulate (variably accelerate) the tempo of beta cell loss and thereby determine the age at onset and incidence of the disease. Some of the predictions made by the hypothesis have been met by data not available when the hypothesis was first proposed. Principle among these is the expectation - now born out in five independent studies - that age at onset should be inversely related to BMI, a surrogate for insulin resistance. This article updates the hypothesis, provides evidence to support the predictions and offers arguments to counter challenges that have appeared in print. Finally, it proposes a randomised controlled trial to test the principle that a reduction in blood glucose, by reducing the load on beta cells, will slow the tempo of their destruction and reduce the incidence of type 1 diabetes.

Role of obesity in complicating and confusing the diagnosis and treatment of diabetes in children

The alarming increase in the prevalence of obesity in children in the United States and globally raises major concerns about its future adverse impact on public health. One outcome of this disturbing trend that is already evident is the rapidly increasing incidence of type 2 diabetes at all ages. This disease, once thought to be nonexistent in children, is increasing coincident with obesity. This article addresses the role that obesity plays in type 2 diabetes and also explores its effects on other types of diabetes that occur in childhood. The new challenges for physicians who formulate a differential diagnosis of diabetes in children are discussed. Also examined are modifications of traditional diabetes treatment that can be helpful in combating the insulin resistance associated with obesity and that use medications that are not traditionally used in this age group. Cases are presented to illustrate certain points. An underlying thesis suggests that specific classification may not be as important to the clinician as the understanding of pathophysiologic factors that contribute to hyperglycemia in individual patients. Recommendations are offered to the practitioner for diagnosing and treating the obese child or adolescent with diabetes.

Family history of diabetes, autoimmunity, and risk factors for cardiovascular disease among children with diabetes in the SEARCH for Diabetes in Youth Study

BACKGROUND

While type 1 diabetes and type 2 diabetes (T2D) are considered etiologically distinct, mixed features of autoimmunity and insulin resistance are increasingly common. We explored a familial contribution to this admixture by evaluating diabetes family history (FH) and its relationship to diabetes type, ethnicity, age at diagnosis, and cardiovascular risk factors in SEARCH for Diabetes in Youth Study participants.

METHODS

Diabetes FH was assessed by questionnaire, with FH categories defined by relative's(s') age at diagnosis as follows: <25 (early FH), >/=25 (later FH), and both <25 and >/=25 (mixed FH). Diabetes type was classified based on a biochemical algorithm using diabetes autoantibodies and fasting C-peptide (FCP).

RESULTS

A positive FH was common in all diabetes types, particularly T2D (83%). Minorities were more likely to have a positive FH than non-Hispanic Whites [odds ratio (OR) 1.96, 95% confidence interval (CI) 1.69-2.27]. The likelihood of having an early FH decreased with age at diagnosis (OR 0.95, 95% CI 0.93-0.98), and the likelihood of having a later/mixed or any positive FH increased with age (OR 1.03, 95% CI 1.01-1.04; OR 1.03, 95% CI 1.02-1.05, respectively). Higher FCP concentrations and less desirable values for almost all cardiovascular risk factors were associated with a later/mixed FH. The association between a later/mixed FH and FCP, body mass index, waist circumference, triglycerides, and high-density lipoprotein remained significant in a subgroup of autoimmune participants.

CONCLUSIONS

Later FH confers cardiovascular risk factors in diabetic youth, including those youth with islet cell autoimmunity. This characterization of diabetes FH may provide a better understanding of familial contributors to diabetes.

Autoantibody epitopes to the smaller isoform of glutamate decarboxylase do not differ in Swedish and Japanese type 1 diabetes patients and may be associated with high-risk human leucocyte antigen class II alleles

Type 1 diabetes (T1D) is an autoimmune disease with a strong human leucocyte antigen (HLA) class II association. Depending on geographic locations, the disease-associated HLA class II alleles vary. We evaluated the beta cell-specific autoimmunity reflected in autoantibodies directed to the smaller isoform of glutamate decarboxylase (GAD65) in Japanese and Swedish T1D patients. GAD65Ab epitope specificities were assessed using GAD65-specific recombinant Fab. GAD65Ab epitope specificities did not differ between Swedish and Japanese patients. Only recognition of the MICA-4-defined middle epitope was significantly stronger in the Japanese T1D patient group compared to the Swedish T1D patients (P = 0.001). Binding to the b96.11-defined middle epitope was substantial in both groups and showed significant associations with high-risk HLA class II haplotypes. In the Japanese T1D group the association was with haplotype DRB1*0802-DQB1*0302 (P = 0.0008), while in the Swedish T1D patients binding to the b96.11-defined epitope as associated with the presence of high-risk HLA genotypes DR3-DQB1*0201 and/or DR4-DQB1*0302 (P = 0.02). A significant association between reduction in binding in the presence of recombinant Fab (rFab) DPD and high-risk allele DQB1*0201 was found (P = 0.008) in the Swedish T1D patients only. We hypothesize that epitope-specific autoantibodies effect the peptide presentation on HLA class II molecules by modulating antigen uptake and processing. Molecular modelling of the high-risk HLA class II molecules will be necessary to test whether these different molecules present similar peptide-binding specificities.

‘Sensing’ autoimmunity in type 1 diabetes

Type 1 diabetes (T1D) results from autoimmune-mediated loss of insulin-producing beta-cells. Recent findings suggest that the events controlling T1D development are not only immunological, but also neuronal in nature. In the non-obese diabetic (NOD) mouse model of T1D, a mutant sensory neuron channel, TRPV1, initiates chronic, progressive beta-cell stress, inducing islet cell inflammation. This novel mechanism of organ-specific damage requires a permissive, autoimmune-prone host, but ascribes tissue specificity to the local secretory dysfunction of sensory afferent neurons. In NOD mice, normalizing this neuronal function by administration of the neurotransmitter substance P clears islet cell inflammation, reduces insulin resistance and restores normoglycemia. Here, we discuss this neuro-immuno-endocrine model, its implications and the involvement of sensory neurons in other autoimmune disorders. These developments might provide novel neuronal-based therapeutic interventions, particularly in diabetes.

Prevalence and clinical features of type 1.5 diabetes mellitus in children

AIM

To classify children with diabetes mellitus as type 1, 1.5 or 2, based on strict criteria, and then compare their features and treatment.

METHODS

In this retrospective study, all children with diabetes mellitus in our clinic with antibody status available (n = 120) were reclassified as type 1, 1.5 or type 2 based on status of antibodies to the pancreas and presence of obesity and/or acanthosis nigricans, and their features compared.

RESULTS

Sixty-four percent of type 2 patients were reclassified as type 1.5. Type 1.5 patients had significantly lower BMI SDS, blood pressure and acanthosis nigricans than type 2 patients. They had a higher insulin requirement (0.82 +/- 0.44 U/kg/day) than type 1 (0.72 +/- 0.35 U/kg/day) or type 2 (0.28 +/- 0.3 U/kg/day) patients. Total cholesterol, HDL-cholesterol, ALT and AST significantly worsened from type 1 to 1.5 to type 2 patients.

CONCLUSIONS

Type 1.5 diabetes mellitus should be considered among obese adolescents presenting as type 2, as their clinical course is more aggressive and insulin requirement higher.

A high incidence of type 1 diabetes and an alarming increase in the incidence of type 2 diabetes among young adults in Finland between 1992 and 1996

AIMS/HYPOTHESIS

The aim of this study was to examine the incidence and trends of type 1 and type 2 diabetes in the 15-39 year-old population between 1992 and 1996 in Finland.

SUBJECTS AND METHODS

Data on the nationwide incidence of diabetes were obtained from four data sources: standardised reports from diabetes nurses, the Finnish National Hospital Discharge Register, the Drug Reimbursement Register and the Drug Prescription Register. The inclusion criterion was consistency in the diagnosis of diabetes across at least two data sources. The sex- and age-specific incidence was calculated for 5-year age groups, both for type 1 and type 2 diabetes. The effects of age, sex and year of diagnosis were assessed by fitting the linear regression model to the incidence data.

RESULTS

Between 1992 and 1996 the age-adjusted incidence of type 1 diabetes among 15-39 year olds was 15.9 per 100,000/year. The incidence was highest among the 15-19 year olds and decreased with age. Conversely, the incidence of type 2 diabetes was very low among 15-19 year olds and increased with age. The total age-adjusted incidence of type 2 diabetes among 15-39 year olds was 11.8 per 100,000/year. The average annual increase in the incidence of type 2 diabetes was 7.9% (95% CI 3.7-12.2%).

CONCLUSIONS/INTERPRETATION

The age at which the Finnish population is at risk of type 1 diabetes extends into young adulthood. The rapid increase in the incidence of type 2 diabetes in the young adult population is a current public health problem.

A new expression of diabetes: double diabetes

Diabetes is on the increase worldwide. The incidence of both type 1 and type 2 diabetes has shown a rise, in parallel with a notable increase in the incidence of a new expression of the disease in children and adolescents, with the characteristics of a mixture of the two types of diabetes, and referred to as 'double diabetes'. Insulin resistance and obesity, together with the presence of markers of pancreatic autoimmunity - namely, autoantibodies to islet cell antigens - typically define this condition. However, recognition of double diabetes can pose problems. In most cases, a reduction in the 'autoimmune load' and an increase in the 'metabolic load' are helpful for attaining a correct diagnosis in a diabetic child.

Molecular characterization of a disease associated conformational epitope on GAD65 recognised by a human monoclonal antibody b96.11

Autoantibodies to the 65kDa isoform of glutamate decarboxylase (GAD65) are associated with type I diabetes and recognise highly conformational epitope(s) that remain to be defined. The human recombinant Fab from mAb b96.11 inhibits binding of most GAD65 antibody positive sera from patients and its epitope has previously been localized to the middle region of GAD65. Recent studies indicate that b96.11 antibody specificity predicts the risk of developing type 1 diabetes in prediabetic individuals. We describe the use homology modelling, protein-protein docking simulations and biopanning of random peptide phage displayed libraries with b96.11 to predict contact amino acids on the interface of GAD65/Fab b96.11 complex. Further analysis by in vitro mutagenesis of GAD65 followed by radioimmunoprecipitation refined the amino acids contributing to the b96.11 epitope. Our studies show an interface characterized by a protruding antibody-combining site centered on the long heavy chain CDR3 loop of Fab b96.11 establishing interactions with the critical residue Phe(344) in the core of the epitope on GAD65, surrounded by charged sites within (375)RK(376) and (305)DER(307). The epitope requires residues from both middle and the C-terminal domains, and is the first precise definition of an epitope on GAD65. The nature of the b96.11 epitope leads to considerations of potential structural variations for differences in antigenicity between the isoforms GAD65 and GAD67. The study shows the utility of using a combination of in silico techniques and experimental data for molecular characterization and localization of conformational epitopes for which crystal structures are lacking.

The great weight gain experiment, accelerators, and their implications for autoantibodies in diabetes

Perspective on the paper by Reinehr et al (see page 473)

What type of diabetes do young people have?

Although type 1 diabetes remains the most common type of diabetes in the pediatric population, there has been a dramatic rise in type 2 diabetes in youth. Clinical distinctions between these two major types have become blurred. As genetic and biochemical measures become more affordable and available, practical applications of these measures to better understand diabetes type in youth and the implications of diabetes type on the evolution of the disease are needed.