Relationships between Islet-Specific Autoantibody Titers and the Clinical Characteristics of Patients with Diabetes Mellitus

Relationship between β-Cell Autoantibodies and Their Combination with Anthropometric and Metabolic Components and Microvascular Complications in Latent Autoimmune Diabetes in Adults

AIMS

Our study aimed to investigate the relationship between three autoantibodies and their combination with anthropometric and metabolic components and microvascular complications in patients with latent autoimmune diabetes in adults (LADA).

METHODS

Our study included 189 LADA patients divided into four subgroups according to the autoantibodies present: glutamic acid decarboxylase autoantibodies (GADA) only; zinc transporter-8 autoantibodies (ZnT8A)+GADA; insulinoma-associated-2 autoantibodies (IA-2)+GADA; and ZnT8+IA-2+GADA.

RESULTS

Compared to GADA positivity only, patients with ZnT8+GADA positivity and ZnT8+IA-2+GADA positivity had a shorter diabetes duration and lower body mass index (BMI); patients with ZnT8+GADA positivity were younger and showed an increase in glomerular filtration rate, while those with ZnT8+IA-2+GADA positivity had lower C-peptide and lower insulin resistance measured with HOMA2-IR. In a multiple regression analysis, ZnT8 positivity was associated with lower BMI (p = 0.0024), female sex (p = 0.0005), and shorter duration of disease (p = 0.0034), while IA-2 positivity was associated with lower C-peptide levels (p = 0.0034) and shorter diabetes duration (p = 0.02). No association between antibody positivity and microvascular complications of diabetes, including retinopathy, neuropathy, and microalbuminuria, as well as with variables of glucose control and β-cell function were found.

CONCLUSION

The results of our study suggest that ZnT8 and IA-2 autoantibodies are present in a significant number of LADA patients and associated with clinical and metabolic characteristics resembling classic type 1 diabetes. Due to increased LADA prevalence, earlier identification of patients requiring frequent monitoring with the earlier intensification of insulin therapy might be of special clinical interest.

The longitudinal loss of islet autoantibody responses from diagnosis of type 1 diabetes occurs progressively over follow-up and is determined by low autoantibody titres, early-onset, and genetic variants

The clinical usefulness of post-diagnosis islet autoantibody levels is unclear and factors that drive autoantibody persistence are poorly defined in type 1 diabetes (T1D). Our aim was to characterise the longitudinal loss of islet autoantibody responses after diagnosis in a large, prospectively sampled UK cohort. Participants with T1D [n = 577] providing a diagnosis sample [range -1.0 to 2.0 years] and at least one post-diagnosis sample (<32.0 years) were tested for autoantibodies to glutamate decarboxylase 65 (GADA), islet antigen-2 (IA-2A), and zinc transporter 8 (ZnT8A). Select HLA and non-HLA SNPs were considered. Non-genetic and genetic factors were assessed by multivariable logistic regression models for autoantibody positivity at initial sampling and autoantibody loss at final sampling. For GADA, IA-2A, and ZnT8A, 70.8%, 76.8%, and 40.1%, respectively, remained positive at the final sampling. Non-genetic predictors of autoantibody loss were low baseline autoantibody titres (P < 0.0001), longer diabetes duration (P < 0.0001), and age-at-onset under 8 years (P < 0.01--0.05). Adjusting for non-genetic covariates, GADA loss was associated with low-risk HLA class II genotypes (P = 0.005), and SNPs associated with autoimmunity RELA/11q13 (P = 0.017), LPP/3q28 (P = 0.004), and negatively with IFIH1/2q24 (P = 0.018). IA-2A loss was not associated with genetic factors independent of other covariates, while ZnT8A loss was associated with the presence of HLA A*24 (P = 0.019) and weakly negatively with RELA/11q13 (P = 0.049). The largest longitudinal study of islet autoantibody responses from diagnosis of T1D shows that autoantibody loss is heterogeneous and influenced by low titres at onset, longer duration, earlier age-at-onset, and genetic variants. These data may inform clinical trials where post-diagnosis participants are recruited.

MiRNA-27a mediates insulin resistance in 3T3-L1 cells through the PPARγ

The biological actions of insulin have been originated by activation of membrane receptors, which trigger a diversity of signaling pathways in facilitating their biological activities. Insulin homeostasis functions in promoting metabolism balance and promotes cell growth and proliferation. If these mechanisms are reformed, this could lead to insulin resistance as a result of defective insulin signaling triggered by mutations in receptors or effector molecules located downstream or by abnormal posttranslational modifications. The purpose of this is to preliminarily investigate the mechanism of miRNA-27a-mediating insulin resistance in 3T3-L1 cells. Insulin resistance in 3T3-L1 adipocytes as a cell model was induced by tumor necrosis factor-alpha (TNF-α) and the miRNA-27a expression in 3T3-L1 adipocytes had been experiential. The regulation of peroxisome proliferator-activated receptor-gamma (PPARγ) mRNA by miRNA-27a had been studied by reverse transcription receptor polymerase chain reaction (RT-PCR). MiRNA-27a was up-regulated in 3T3-L1 cells, miRNA-27a mimics reserved expression of PPARγ mRNA, and miRNA-27a inhibitors up-regulated the expression of PPARγ mRNA. The insulin resistance in 3T3-L1 cells mediated by miRNA-27a may be achieved by targeting PPARγ.

Correlation between Insulin Resistance and Microalbuminuria Creatinine Ratio in Postmenopausal Women

OBJECTIVE

To study the relationship between insulin resistance and urinary microalbumin creatinine ratio in postmenopausal women.

METHODS

The selected research group comprised 104 postmenopausal women with type 2 diabetes who were admitted to the Department of Endocrinology in the green card center at the First Affiliated Hospital of Hainan Medical University between 2017 and 2019 inclusive. Ninety-eight postmenopausal women with the normal blood glucose metabolism hospitalized in the same period were used as the control group. The age, body mass index, systolic blood pressure (SBP), diastolic blood pressure (DBP), heart rate, fasting blood glucose, fasting insulin (FINS), glycosylated hemoglobin (HbA1c), total cholesterol (TC), triglyceride (TG), high-density lipoprotein (HDL-C), low-density lipoprotein (LDL-C), and urinary albumin-creatinine ratio (UACR) were analyzed. The insulin resistance index (HOMR-IR) was calculated, and the correlation between IR and UACR was analyzed.

RESULTS

Levels of HOMA-IR, SBP, HbA1c, HDL-C, LDL-C, TC, TG, FPG, FINS, and UACR in the study group were higher than those in the control group, and a significant difference was found between the groups (P < 0.05). The level of DBP in the study group was lower than that in the control group, and the difference was statistically significant (P < 0.05). Pearson correlation analysis showed that UACR was positively correlated with HOMA-IR and HbA1c (r = 0.254, r = 0.565, P < 0.01). Multiple linear stepwise regression analysis further showed that HOMA-IR and age were positively correlated with UACR (P < 0.05).

CONCLUSION

There is a correlation between IR and UACR in postmenopausal women. IR is an independent risk factor for UACR.