Hyperadiponectinemia is independent of kidney function, diabetes duration, and control in type 1 diabetic patients without microangiopathy

Serum adiponectin concentrations as a risk factor for cardiovascular complications in type 1 diabetes

AIM

By analyzing data from DCCT/EDIC study, we investigated the associations of serum adiponectin concentrations with macrovascular complications and cardiovascular events in T1D.

MATERIALS AND METHODS

Adiponectin concentrations were measured in EDIC year 8. The participants (n = 1040) were divided into four groups by quartiles of adiponectin concentrations. The association of macrovascular complications and cardiovascular events were analyzed by using multivariable regression and Cox proportional hazards models.

RESULTS

High adiponectin concentrations were associated with decreased risk of peripheral artery disease represented by ankle brachial index (ORs (95% CI): 0.22 (0.07-0.72), 0.48 (0.18-1.25), and 0.38 (0.14-0.99) in fourth, third, and second quartiles compared with first quartile), with reduced carotid intima-media thickness, and with increased LVEDV index. Moreover, high adiponectin concentrations were also associated with increased risk of any cardiovascular events (HRs (95% CI): 2.59 (1.10-6.06), 2.03 (0.90-4.59), and 1.22 (0.52-2.85)) and major atherosclerotic cardiovascular events (HRs (95% CI): 11.37 (2.04-63.43), 5.68 (1.04-31.07), and 3.76 (0.65-21.77) in fourth, third, and second quartiles compared with first quartile), however, after adjustments with LVEDV index, these associations were diminished.

CONCLUSIONS

Adiponectin may protect carotid atherosclerosis and peripheral artery disease in T1D. It may be associated with increased cardiovascular events, depending on cardiac structural changes.

Adiponectin receptor fragmentation in mouse models of type 1 and type 2 diabetes

The protein hormone adiponectin regulates glucose and fatty acid metabolism by binding to two PAQR-family receptors (AdipoR1 and AdipoR2). Both receptors feature a C-terminal segment which is released by proteolysis to form a freely circulating C-terminal fragment (CTF) found in the plasma of normal individuals but not in some undefined diabetes patients. The AdipoR1-CTF_344–376 is a competitive inhibitor of tumor necrosis factor α cleavage enzyme (TACE) but it contains a shorter peptide domain (AdipoR1 CTF_351–362) that is a strong non-competitive inhibitor of insulin-degrading enzyme (IDE). The link between adiponectin receptor fragmentation and diabetes pathology is unclear but could lead to new therapeutic strategies. We therefore investigated physiological variations in the concentrations of CTF in non-obese diabetic (NOD/ShiLtJ) mice and C57BL/6 mice with diet-induced obesity (DIO) as models of diabetes types 1 and 2, respectively. We tested for changes in adiponectin receptor signaling, immune responses, disease progression, and the abundance of neutralizing autoantibodies. Finally, we administered exogenous AdipoR1-CTF peptides either containing or lacking the IDE-binding domain. We observed the more pronounced CTF shedding in the TACE-active NOD mice, which represents an inflammatory autoimmune phenotype, but fragmentation was also observed to a lesser extent in the DIO model. Autoantibodies to CTF were detected in both models. Neither exogenous CTF peptide affected IgG-CTF plasma levels, body weight or the conversion of NOD mice to diabetes. The pattern of AdipoR1 fragmentation and autoantibody production under physiological conditions of aging, DIO, and autoimmune diabetes therefore provides insight into the association adiponectin biology and diabetes.

Association between serum/plasma adiponectin levels and immune-mediated diseases: a meta-analysis

Adiponectin plays an important role in the development of immune-mediated diseases. Currently published data regarding the relationship between serum/plasma levels of adiponectin and immune-mediated diseases are inconsistent. We therefore conducted this meta-analysis to explore the association of serum/plasma adiponectin levels with immune-mediated diseases in humans. Systematic literature search was conducted to identify all relevant studies. The study quality was assessed by the Newcastle-Ottawa scale. Pooled standard mean difference (SMD) with 95% confidence interval (CI) was calculated by random-effect model analysis. A total of 47 studies were included in our meta-analysis, including 27 studies of type 1 diabetes mellitus (T1DM), 9 studies of rheumatoid arthritis (RA), 7 studies of systemic lupus erythematosus (SLE), and 4 studies of ankylosing spondylitis (AS). The results revealed significant differences in serum/plasma levels of adiponectin between immune-mediated diseases and normal controls (SMD = 1.262, 95% CI 0.766-1.758, p < 0.001). In the subgroup analysis stratified by disease type, the serum/plasma levels of adiponectin in T1DM, RA and SLE patients were higher than those in normal control, but not in AS patients. Moreover, in the subgroup analysis stratified by gender, in both men and women group, the serum/plasma levels of adiponectin in patients with immune-mediated diseases were higher than that in the control group. Furthermore, subgroup analyses also showed that immune-mediated diseases from Asian population, Caucasian population, mean age >40 years, and BMI ≥24 kg/m² had higher serum/plasma adiponectin levels when compared with normal controls. Collectively, this meta-analysis demonstrates that serum/plasma levels of adiponectin in T1DM, RA and SLE patients were higher than those in normal controls, but not in AS patients.

Serum adiponectin helps to differentiate type 1 and type 2 diabetes among young Asian Indians

OBJECTIVE

This study assessed whether serum adiponectin could be used as a biochemical marker to differentiate type 1 diabetes mellitus (T1DM) from type 2 diabetes mellitus (T2DM) among young Asian Indians.

RESEARCH DESIGN AND METHODS

We recruited age- and sex-matched individuals with physician-diagnosed T1DM (n=70) and T2DM (n=72). All were 12-27 years of age with a duration of diabetes of >2 years, at a large tertiary-care diabetes center in Chennai, southern India. Age- and sex-matched individuals with normal glucose tolerance (NGT) (n=68) were selected from an ongoing population study. NGT was defined using World Health Organization criteria. Serum total adiponectin was measured by enzyme-linked immunosorbent assay. Receiver operating characteristic (ROC) curves were used to identify adiponectin cut points for discriminating T1DM from T2DM.

RESULTS

Adiponectin levels were higher in T1DM and lower in T2DM compared with the NGT group (9.89, 3.88, and 6.84 μg/mL, respectively; P<0.001). In standardized polytomous regression models, adiponectin was associated with T1DM (odds ratio [OR]=1.131 per SD; 95% confidence interval [CI], 1.025-1.249) and T2DM (OR=0.628 per SD; 95% CI, 0.504-0.721) controlled for age, gender, waist circumference, body mass index, hypertension, glycated hemoglobin, total cholesterol, serum triglycerides, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, family history of T2DM, and estimated glomerular filtration rate. Using ROC analysis, an adiponectin cut point of 5.1 μg/mL had a C statistic of 0.886 (95% CI, 0.836-0.953), sensitivity of 80.6%, and specificity of 80.6% to differentiate T1DM from T2DM. Using the 5.1 μg/mL cut point, 80.6% of T1DM and 81.8% of T2DM would be correctly classified.

CONCLUSIONS

Serum adiponectin is a useful biochemical marker for differentiating T1DM and T2DM among young Asian Indians.