No signs of progressive beta cell damage during 20 years of prospective follow-up of autoantibody-negative diabetes

Exploring the potential role of C-peptide in type 2 diabetes management

Type 2 diabetes (T2D) is a complex condition characterised by the interaction between insulin resistance and beta cell dysfunction. C-peptide, a key biomarker of endogenous insulin secretion, has a role in diagnosing type 1 diabetes (T1D). However, its utility in T2D has not been extensively studied. This review provides an overview of the progression of C-peptide levels over time in T2D and discuss its interpretation in clinical settings. We reviewed current evidence on the relationship between C-peptide levels and response to antidiabetic drugs, as well as the utility of C-peptide testing in T2D treatment strategies. We also reviewed available evidence for C-peptide in predicting future outcomes in T2D. In this review, we hoped to clarify the value of C-peptide testing in understanding and managing T2D and to highlight areas where further research is needed.

[Effects of glycosylated hemoglobin and disease course on islet β-cell function in patients with type 2 diabetes]

OBJECTIVE

To compare islet β-cell function in type 2 diabetic (T2DM) patients with different glycosylated hemoglobin (HbA1c) levels and diabetes durations.

METHODS

We examined body parameters, biochemical profiles and islet autoantibodies in a total of 803 T2DM patients admitted in the Department of Endocrinology of the First Affiliated Hospital of Nanjing Medical University between December, 2014 and April, 2016. The patients were stratified by HbA1c level and disease course and underwent steamed bun test to evaluate islet β-cell function and insulin resistance.

RESULTS

Linear correlation analysis showed that in T2DM patients, HbA1c level was negatively correlated with HOMA2-IR, HOMA2-%β, DI30 and DI180 (P=0.000), and disease course was negatively correlated with HOMA2-IR, HOMA2-% β, and DI180 (P < 0.05). The patients with different HbA1c levels showed significantly different HOMA2-IR, HOMA2-%β, DI30 and DI180 (P=0.000); HOMA2-%β, DI30 and DI180 were significantly higher in patients with HbA1c levels < 7.8%, and HOMA2-% β was significantly decreased in patients with HbA1c levels above 9.8%. The patients with different disease courses also had significant differences in HOMA2-IR, HOMA2-%β, DI30, and DI180 (P=0.000), and as the disease course extended, DI30 and DI180 tended to decrease progressively. Multivariate linear regression analysis showed that HbA1c, diabetes duration, and body mass index (BMI) were all independent factors affecting islet β- cell function in T2DM patients.

CONCLUSIONS

The secretion function of islet β cells decreases progressively with the increase of HbA1c level or disease course in T2DM patients, but the disease course does not appear to have an effect as strong as that of HbA1c level on islet β cell function.

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 association of PTPN22 rs2476601 polymorphism and CTLA-4 rs231775 polymorphism with LADA risks: a systematic review and meta-analysis

Although the polymorphisms of PTPN22 and the variants of CTLA-4 have been reported to be the susceptibility genes, which increased risk of latent autoimmune diabetes in adults (LADA), the results remained inconclusive. The aim of this meta-analysis was to evaluate the association between the polymorphisms of two genes and LADA. We performed a systematic review by identifying relevant studies and applied meta-analysis to pool gene effects. Data from ten studies published between 2001 and 2013 were pooled for two polymorphisms: rs2476601 in the PTPN22 gene and rs231775 in the CTLA-4 gene. Data extraction and assessments for risk of bias were independently performed by two reviewers. Fixed-effect model and random-effect model were used to pool the odds ratios; meanwhile, heterogeneity test, publication bias and sensitive analysis were explored. The minor T allele at rs2476601 and the minor G at rs231775 carried estimated relative risks (odds ratio) of 1.52 (95 % CI 1.29-1.79) and 1.39 (95 % CI 1.11-1.74), respectively. These alleles contributed to an absolute lowering of the risk of all LADA by 4.88 and 14.93 % when individuals do not carry these alleles. The estimated lambdas were 0.49 and 0.63, suggesting a codominant model of effects was most likely for two genes. In summary, our systematic review has demonstrated that PTPN22 rs2476601 and CTLA-4 rs231775 are potential risk factors for LADA. An updated meta-analysis is required when more studies are published to increase the power of these polymorphisms and LADA.

Neuropeptide Y autoantibodies in patients with long-term type 1 and type 2 diabetes and neuropathy

AIMS

The neurotransmitter Neuropeptide Y (NPY) was previously reported as a minor autoantigen in newly diagnosed type 1 diabetes (T1D) patients. The single nucleotide polymorphism at rs16139 (T1128C, L7P) in the NPY gene was associated with an increased risk for the development of type 2 diabetes (T2D). We aimed to develop a radiobinding assay for NPY-L (Leucine) and NPY-P (Proline) autoantibodies (A) to study the levels and the association with other islet autoantibodies and neuropathy.

METHODS

Autoantibodies against NPY-L, NPY-P, ZnT8, GAD65 and IA-2 were studied in T1D (n=48) and T2D (n=26) patients with duration up to 42 and 31years. A subgroup of T1D (n=32) patients re-examined, 5-8years after first visit, was tested for peripheral (Z-score) and autonomic neuropathy (E/I ratio).

RESULTS

NPY-LA and NPY-PA were detected in 23% and 19% in T1D (p<0.001), and 12% and 23% in T2D patients (p<0.001) compared to 2.5% controls (n=398). The levels of NPYA declined during follow-up in the T1D patients (p<0.001). The neuropathy was not related to the NPYA or the other islet autoantibodies.

CONCLUSIONS

Regardless of the absence of an association between NPYA and neuropathy, NPY may contribute to the pathogenesis of T1D and T2D as a minor autoantigen.

Impaired vibrotactile sense at low frequencies in fingers in autoantibody positive and negative diabetes

Vibration thresholds in index and little finger pulps in subjects with autoantibody [GADA, IA-2A and/or ICA] positive and negative diabetes 20 years after diagnosis were higher than in age-matched controls at low frequencies (8 and 16 Hz), irrespective of HbA1c values, indicating selective impairment of Meissner's corpuscles and/or their innervating axons.

Progressive deterioration of β-cell function in obese youth with type 2 diabetes

OBJECTIVE

In adults, type 2 diabetes (T2DM) is characterized with progressive deterioration in insulin secretion. Data are scanty in youth. We investigated prospectively the change in β-cell function and in insulin sensitivity in youth with T2DM.

RESEARCH DESIGN AND METHODS

Six adolescents with T2DM [hemoglobin A1c (HbA1c) 6.6 ± 1.0%] underwent evaluation of hepatic glucose production (HGP; [6,6-²H₂] glucose), insulin-stimulated glucose disposal (Rd; hyperinsulinemic-euglycemic clamp), first- and second-phase insulin/C-peptide secretion (hyperglycemic clamp), body composition dual energy X-ray absorptiometry (DEXA), and abdominal adiposity (computed tomography) within 3 yr of the diagnosis of diabetes and after 12-16 months of follow-up.

RESULTS

Weight, body mass index (37.1 ± 6.9), HbA1c (6.3 ± 0.7%), HGP (2.8 ± 1.2 mg/kg/min), and Rd (4.9 ± 3.4 mg/kg/min) did not change significantly from baseline. However, first-phase insulin and C-peptide declined (152.6 ± 261.2 vs. 75.9 ± 108.5 μU/mL, p = 0.028; 8.0 ± 6.3 vs. 5.9 ± 4.4 ng/mL, p = 0.048, respectively) with no significant change in second-phase insulin/C-peptide. The rate of decline in β-cell function was ∼20% per year.

CONCLUSIONS

After a median duration of 20 months of diabetes, youth with T2DM manifest a rapid decline in β-cell function with no significant changes in peripheral or hepatic insulin sensitivity. Interventions to retard this deterioration in β-cell function should be investigated.

Fulminant type 1 diabetes: a collaborative clinical cases investigation in China

To clarify the detailed distribution, clinical and immunological features of patients with fulminant type 1 diabetes (F1D), we consecutively investigated 53 cases from nationwide 24 hospitals in China. After the clinical and immunological features were evaluated, we compared pregnancy-associated F1D (PF) with those of child-bearing age with F1D that was not associated with pregnancy in clinical characteristics. As a result, patients with F1D were reported from all over China, and there was no significant regional and seasonal preference of this disease. Around 34.0% (18/53) patients displayed low titers of autoantibodies against one or more autoantigens, including 12 cases positive for GADA, 2 for IA-2A, 4 for ZnT8A and 3 for both GADA and ZnT8A. The frequency of PF in female F1D was 34.6% (9/26). Among 9 PF patients, 8 (88.9%) developed F1D during pregnancy which resulted in stillbirth, while one had the onset of F1D after eutocia with her fetus survived. This study suggests that islet-associated autoimmunity may be involved in and contribute to the development of F1D. Pregnant women may be PF high-risk population, and the prognosis for the fetus is extremely poor in PF patients.

Clinical evolution of beta cell function in youth with diabetes: the SEARCH for Diabetes in Youth study

AIMS/HYPOTHESIS

Few studies have explored the epidemiology of beta cell loss in youth with diabetes. This report describes the evolution and major determinants of beta cell function, assessed by fasting C-peptide (FCP), in the SEARCH for Diabetes in Youth study.

METHODS

Participants were 1,277 youth with diabetes (948 positive for diabetes autoantibodies [DAs] and 329 negative for DAs), diagnosed when aged <20 years, who were followed from a median of 8 months post diagnosis, for approximately 30 months. We modelled the relationship between rate of change in log FCP and determinants of interest using repeated measures general linear models.

RESULTS

Among DA-positive youth, there was a progressive decline in beta cell function of 4% per month, independent of demographics (age, sex, race/ethnicity), genetic susceptibility to autoimmunity (HLA risk), HbA(1c) and BMI z score, or presence of insulin resistance. Among DA-negative youth, there was marked heterogeneity in beta cell loss, reflecting an aetiologically mixed group. This group likely includes youths with undetected autoimmunity (whose decline is similar to that of DA-positive youth) and youth with non-autoimmune, insulin-resistant diabetes, with limited decline (~0.7% per month).

CONCLUSIONS/INTERPRETATION

SEARCH provides unique estimates of beta cell function decline in a large sample of youth with diabetes, indicating that autoimmunity is the major contributor. These data contribute to a better understanding of clinical evolution of beta cell function in youth with diabetes, provide strong support for the aetiological classification of diabetes type and may inform tertiary prevention efforts targeted at high-risk groups.

Autoantibodies to CCL3 are of low sensitivity and specificity for the diagnosis of type 1 diabetes

Type 1 diabetes (T1D) is a T cell-dependent tissue-specific autoimmune disease, characterized by the selective destruction of the β cells of the pancreatic islets of Langerhans. Recently, contradictory findings have been reported about the relationship of autoantibodies to CC chemokine 3 (CCL3) and T1D, which need to be confirmed by more investigations in larger cohorts. The aim of our research was to investigate whether autoantibodies to CCL3 are useful markers for T1D in a large cohort of Chinese patients. We analyzed autoantibodies to CCL3, glutamic acid decarboxylase(GADA), insulinoma-associated protein-2 (IA-2A), and zinc transporter-8 (ZnT8A) by a radioimmunoprecipitation assay in 290 T1D subjects, 200 subjects with type 2 diabetes (T2D), 210 subjects with other diseases, and 178 healthy control subjects. Results showed that the frequencies of autoantibodies to CCL3 in subjects with T1D, T2D, and healthy control subjects were similar [3.10% (9/290), 2.50% (5/200), and 0.56% (1/178), respectively, P = 0.189]. Autoantibodies to CCL3 were not significantly different between T1D patients with or without GADA, IA-2A, or ZnT8A antibodies (2.7% vs. 3.9%, P = 0.725). In contrast, patients with systemic lupus erythematosus and rheumatoid arthritis showed higher positivity for autoantibodies to CCL3 than healthy control subjects [15.6% (5/32) and 12.5% (8/64) vs. 0.56% (1/178), all P = 0.000], and higher titer of autoantibodies to CCL3 than T1D patients (median 0.9633 and 0.4095 vs. 0.0873, P = 0.012 and P = 0.034, respectively). We conclude that autoantibodies to CCL3 are of low sensitivity and specificity for T1D and cannot be used in the diagnosis of T1D.