Comparison of the effects of pioglitazone and voglibose on circulating total and high-molecular-weight adiponectin, and on two fibrinolysis inhibitors, in patients with Type 2 diabetes

The effect of voglibose on metabolic profiles in patients with type 2 diabetes mellitus: A systematic review and meta-analysis of clinical trials

OBJECTIVE

The effect of voglibose on metabolic homeostasis is not well characterized. Therefore, we conducted a systematic review and meta-analysis of clinical trials assessing the effect of voglibose on metabolic profile in patients with type 2 diabetes mellitus (T2DM).

METHODS

Systematic searches were conducted in PubMed, Scopus, Embase, Google Scholar, Web of Science and Cochrane Library to identify clinical trials assessing the effects of voglibose supplementation on cardio-metabolic profile from incept up to 29 July 2019. Data was pooled using fixed- or random-effect models and weighted mean difference (WMD) as the effect size.

RESULTS

Eight clinical trials from 1094 reports, were eligible for inclusion. Pooled findings identified significant reductions in hemoglobin A1c (HbA1c) (WMD= -0.27; 95 %CI -0.49 to -0.05; P = 0.01; I² = 64.8 %) and an increase in LDL-cholesterol levels (WMD=5.97 mg/dl, 95 % CI 0.88, 11.06, P = 0.02; I² = 0.0 %). However, no evidence of effect for voglibose intake on T2DM patients was observed for: fasting blood sugar (FBS) (WMD -7.43 mg/dl; 95 %CI -16.56 to 1.71; P = 0.110; I² = 69.3 %), serum insulin (WMD= -0.15 μU/mL; 95 %CI -0.89 to 0.60; P = 0.70; I² = 0.0 %), total-cholesterol (WMD=2.82 mg/dl, 95 %CI -2.36 to 8.01, P = 0.70; I² = 49.7 %), triglycerides (WMD= -7.07 mg/dl, 95 %CI -21.76 to 7.62, P = 0.34; I² = 0.0 %), HDL-cholesterol levels (WMD= -2.10 mg/dl, 95 %CI -4.48 to 0.27, P = 0.08; I² = 0.0 %,), body mass index (BMI) (WMD=0.09 kg/m², 95 %CI -0.70 to 0.87; P = 0.87; I² = 0.0 %), body weight (WMD= -0.42 kg, 95 %CI -0.84 to 0.00; P = 0.05; I² = 0.0 %), and adiponectin levels (WMD = 0.32 μg/mL, 95 %CI -0.74 to 1.38; P = 0.55; I² = 0.0 %).

CONCLUSIONS

The current meta-analysis identified a decrease in HbA1c and an increase in LDL-cholesterol with administration of voglibose. However, no significant effect was observed on FBS, insulin, bodyweight, BMI, adiponectin, triglycerides, total- and HDL-cholesterol levels.

Meta-analysis and critical review on the efficacy and safety of alpha-glucosidase inhibitors in Asian and non-Asian populations

AIMS/INTRODUCTION

To evaluate the efficacy and safety of alpha-glucosidase inhibitors (AGI) in Asian and non-Asian type 2 diabetes patients.

MATERIALS AND METHODS

Studies were identified through a literature search of MEDLINE, EMBASE and other databases until December 2016. All statistical analyses were carried out in Review Manager statistical software by computing the weighted mean difference or odds ratio and 95% confidence interval.

RESULTS

A total of 67 studies were included. AGI vs placebo: compared with the placebo, AGI treatment led to a greater decrease in hemoglobin A1c (HbA1c), fasting plasma glucose and postprandial plasma glucose. No significant difference was observed in HbA1c change, fasting plasma glucose change, postprandial plasma glucose change or incidence of hypoglycemia between Asian and non-Asian patients. AGI vs active controls: in Asian patients, AGI treatment showed a lower reduction in HbA1c compared with dipeptidyl peptidase-4 inhibitors and sulfonylurea. In non-Asian patients, AGI treatment showed a lower reduction in HbA1c compared with thiazolidinedione. No significant difference was observed in HbA1c change and bodyweight change when comparing AGI with other oral hypoglycemic agents between Asian and non-Asian patients.

CONCLUSIONS

The effects of AGI treatment on glycemic control and bodyweight reduction were superior to the placebo without an increased incidence of hypoglycemia, but with an increased incidence of gastrointestinal discomforts. The hypoglycemic effects of AGI were comparable between Asian and non-Asian patients.

Assembly of adiponectin oligomers

Adiponectin is among the most studied adipokines, the collection of molecules secreted from adipose tissue. It is also one of the most architecturally complex adipokines with its various oligomeric states that include trimers, hexamers, nonamers (9mers), dodecamers (12mers), and octadecamers (18mers). The importance of adiponectin in metabolic regulation is underscored by its strong positive associations with improvement in insulin action and also decreased risks for developing type 2 diabetes. Understanding the mechanisms involved in maintaining the steady-state concentrations of adiponectin oligomers in circulation is therefore likely to provide important insight into the development of insulin resistance. This review will discuss the current state of knowledge regarding the biochemical composition of adiponectin oligomers, the commonly used techniques to analyze them, and the known post-translational modifications that affect their assembly. Evidence based on in vitro oligomer assembly reactions in support of a "cystine ratchet" model of adiponectin oligomer formation will be considered along with limitations of the evidence. Secretory pathway proteins that have been shown to affect the distribution of adiponectin oligomers will also be discussed along with hypotheses regarding their potential involvement in the cystine ratchet model of adiponectin oligomerization.

Adding glimepiride to current insulin therapy increases high-molecular weight adiponectin levels to improve glycemic control in poorly controlled type 2 diabetes

BACKGROUND

To observe the efficacy and safety of adding glimepiride to established insulin therapy in poorly controlled type 2 diabetes (T2D) and to assess the relationship of changes in the serum high-molecular weight (HMW) adiponectin levels and glycemic control after glimepiride treatment.

METHODS

Fifty-six subjects with poorly controlled insulin-treated T2D were randomly assigned to either the glimepiride-added group (the group A, n = 29) or the insulin-increasing group (the group B, n = 27) while continuing current insulin-based therapy. Glycosylated hemoglobin (HbA1c) value, daily insulin dose, body weight, waist circumference, plasma lipid concentration, serum HMW adiponectin level and the number of hypoglycemic events were evaluated before and after treatment.

RESULTS

At the end of study, insulin doses were significantly reduced, and the mean HbA1c, fasting blood glucose (FBG) and 2-hour postprandial blood glucose (P2BG) were improved greater in the group A compared with the group B. The serum HMW adiponectin levels were significantly increased in the group A compared with the group B. Most importantly, we found that changes in HbA1c were inversely correlated with changes in serum HMW adiponectin in the group A (r = -0.452, p = 0.02).

CONCLUSIONS

Adding glimepiride to current insulin treatment led to better improvement in glycemic control with a significant smaller daily insulin dose, and the increases in the serum HMW adiponectin levels may directly contribute to improvement glycemic control.

Reduced high-molecular-weight adiponectin is an independent risk factor for cardiovascular lesions in hypercholesterolaemic patients

BACKGROUND

The hormone adiponectin (APN) circulates in plasma as various multimeric complexes. The high-molecular-weight (HMW) isoform has been reported to exert the most favourable metabolic regulatory and vasculoprotective effects. This study determined the circulatory distribution of APN multimers and their relationships with cardiovascular disease (CVD)-related biochemical indicators in patients with hypercholesterolaemia (HC).

METHODS

A total of 148 male age- and BMI-matched patients with HC (80 with CVD and 68 without CVD) and 84 male healthy controls were enrolled. Diabetes mellitus, hypertension, nephropathy and cigarette use constituted exclusion criteria.

RESULTS

Both HMW and medium-molecular-weight (MMW) forms of APN were significantly increased in HC without CVD (HMW: 4·98 ± 0·87 vs 2·51 ± 0·33 in control, P < 0·01; MMW: 2·20 ± 0·36 vs 1·01 ± 0·15 in control, P < 0·01) and were comparable to control in patients with hypercholesterolaemia with CVD (HCVD). In comparison with other APN oligomers, HMW is most closely associated with the HCVD-related biochemical factors, total cholesterol (r = 0·345, P < 0·05), high-density lipoprotein cholesterol (HDLc, r = 0·325, P < 0·05) and uric acid (UA, r = -0·472, P < 0·01). Additional analysis via binary logistic regression suggests that HMW is an independent predictor of risk of HCVD (OR, 8·434; P = 0·018).

CONCLUSION

These results suggest that reduced HMW isoform concentrations might be considered as an independent risk factor for cardiovascular complications in patients with HC.

Elevation of serum high molecular weight adiponectin in patients with Type 2 diabetes and orthostatic hypotension: association with arterial stiffness and hypercoagulability

AIM

Orthostatic hypotension is a hallmark of diabetic autonomic neuropathy and is associated with increased mortality. The serum level of adiponectin is elevated in patients with heart failure or renal failure. In the present study, we measured serum levels of total and high molecular weight adiponectin in patients with Type 2 diabetes and orthostatic hypotension. We also investigated the relationship between the presence of orthostatic hypotension and various clinical variables in patients with Type 2 diabetes.

METHODS

We studied 105 patients with Type 2 diabetes. Orthostatic hypotension was defined as a decrease of 20 mmHg or more in systolic blood pressure and/or 10 mmHg in diastolic blood pressure when blood pressure was measured for 3 min while standing. The brachial-ankle pulse-wave velocity was also measured as an index of arterial stiffness.

RESULTS

Orthostatic hypotension was found in 30 patients with diabetes (28.6%). The haematocrit and estimated glomerular filtration rate were significantly lower in patients with orthostatic hypotension than in those without it. Brachial-ankle pulse-wave velocity and serum total and high molecular weight adiponectin were significantly higher in patients with orthostatic hypotension than in those without. Furthermore, the high molecular weight/total adiponectin ratio was higher in patients with orthostatic hypotension than in those without and hypertension was more common in patients with orthostatic hypotension. Plasma prothrombin F1 + 2, a coagulation maker, was higher in patients with orthostatic hypotension than in those without, while there were no differences of fibrinolytic markers between the two groups. Multivariate analysis showed that HDL cholesterol, haematocrit, F1 + 2, brachial-ankle pulse-wave velocity and a decline of systolic blood pressure on standing were independent determinants of high molecular weight adiponectin.

CONCLUSIONS

Patients with Type 2 diabetes and orthostatic hypotension had an elevated serum level of high molecular weight adiponectin, which was associated with the simultaneous presence of renal dysfunction, anaemia, arterial stiffness and hypercoagulability.

Plasma thrombin-activatable fibrinolysis inhibitor levels are not associated with glucose intolerance and subclinical atherosclerosis in women with previous gestational diabetes

We aimed to determine plasma thrombin-activatable fibrinolysis inhibitor (TAFI) antigen levels in women with previous gestational diabetes mellitus (GDM) and to evaluate the possible association of plasma TAFI with glucose intolerance and markers of subclinical atherosclerosis. This cross-sectional study was performed in 111 women with previous GDM and 60 controls. Glucose intolerance was evaluated. Homeostasis model assessment score was calculated. Circulating lipids, interleukin-6, matrix metalloproteinase-1, fibrinogen, plasminogen activator inhibitor-1, and TAFI antigen levels were assayed. Carotid intima media thickness (IMT) was measured. Women with previous GDM had increased levels of atherosclerosis markers and carotid IMT. On the other hand, plasma TAFI antigen levels were similar (P = .395). Thrombin-activatable fibrinolysis inhibitor was not associated with the indices of insulin resistance, glucose intolerance, markers of atherosclerosis, and carotid IMT. Our data demonstrated that plasma TAFI was not altered in women with previous GDM. TAFI was not associated with glucose intolerance and subclinical atherosclerosis.

Pharmacological and non-pharmacological interventions to influence adipose tissue function

Obesity is associated with metabolic derangements such as insulin resistance, inflammation and hypercoagulobility which can all be understood as consequences of adipose tissue dysfunction. The potential role for adipose tissue derived cytokines and adipokines in the development of vascular disease and diabetes may produce a clinical need to influence adipose tissue function. Various pharmacological and non-pharmacological interventions affect plasma cytokine and adipokine levels. The effects of these interventions depend on weight loss per se, changes in fat distribution without weight loss and/or direct effects on adipose tissue inflammation.

Weight loss, as a result of diet, pharmacology and surgery, positively influences plasma adipokines and systemic inflammation. Several classes of drugs influence systemic inflammation directly through their anti-inflammatory actions. PPAR-γ agonism positively influences adipose tissue inflammation in several classes of intervention such as the thiazolidinediones and perhaps salicylates, CB1-antagonists and angiotensin II receptor blockers. Furthermore, within drug classes there are differential effects of individual pharmacologic agents on adipose tissue function.

It can be concluded that several commonly used pharmacological and non-pharmacological interventions have unintended influences on adipose tissue function. Improving adipose tissue function may contribute to reducing the risk of vascular diseases and the development of type 2 diabetes.

Determinants of serum high molecular weight (HMW) adiponectin levels in patients with coronary artery disease: associations with cardio-renal-anemia syndrome

OBJECTIVE

A low serum adiponectin level is associated with a high incidence of coronary artery disease (CAD) in the healthy population. Paradoxically, serum adiponectin is elevated in patients with severe CAD or chronic heart failure. We investigated the determinants of serum high molecular weight (HMW) adiponectin in patients with CAD.

PATIENTS AND METHODS

We studied 228 consecutive patients with CAD confirmed by angiography. Anemia was defined as a hemoglobin of <13.0 g/dL in men and<12.0 g/dL in women. A high plasma B-type natriuretic-peptide (BNP) was defined as >100 pg/mL. Chronic kidney disease (CKD) was defined as an estimated glomerular filtration rate (eGFR) of <60 mL/min for more than 3 months. The patients with CAD were divided into eight groups according to the presence or absence of anemia, high BNP, and/or CKD.

RESULTS

In all 228 patients with CAD, serum HMW adiponectin correlated positively with age, high-density-lipoprotein cholesterol (HDL-C), and BNP, while this parameter showed negative correlations with body mass index, insulin resistance, triglycerides, eGFR, and hemoglobin. Multivariate analysis showed that HDL-C, BNP, gender, and age were independently associated with the HMW adiponectin. Serum HMW adiponectin was lower in CAD patients with than without metabolic syndrome. Serum HMW adiponectin and the HMW/total adiponectin ratio were highest in CAD patients who had anemia, high BNP, and CKD among the groups.

CONCLUSION

In patients with CAD, metabolic syndrome is associated with a lower serum HMW adiponectin, while the presence of anemia, high BNP, and CKD is associated with elevation of the serum HMW adiponectin.

Relationship of high-molecular-weight adiponectin levels to visceral fat accumulation in hemodialysis patients

OBJECTIVE

High molecular weight adiponectin (HMW ADPN) plays an important role in the regulation of insulin resistance and atherogenic processes. However, the role of HMW ADPN remains to be determined in hemodialysis (HD) patients.

PATIENTS AND METHODS

We measured serum HMW ADPN in 49 HD patients (age: 62.4+/-12.0 years, time on HD: 8.4+/-6.4 years, male/female=30/19), and examined the association between HMW ADPN and visceral fat area (VFA) estimated by abdominal CT scans.

RESULTS

Serum HMW ADPN concentrations were weakly and inversely correlated with serum TG (r=-0.271, p=0.0598), but significantly and positively correlated with HDL cholesterol (r=0.392, p=0.0050). Serum HMW ADPN levels were positively correlated with BMI (r=0.472, p=0.0084) in male patients, and the HMW ADPN levels were positively correlated with serum levels of HDL cholesterol (r=0.514, p=0.0243) and TG (r=0.605, p=0.0061).The regression coefficient between VFA and HMW ADPN was -0.491 (p<0.003). Multiple stepwise regression analyses showed that VFA was the most significant and independent determinant of serum HMW ADPN concentration.

CONCLUSION

These findings suggest that HMW ADPN may be inversely associated with visceral fat accumulation in HD patients.

Anemia is associated with an elevated serum level of high-molecular-weight adiponectin in patients with type 2 diabetes independently of renal dysfunction

Low serum adiponectin is associated with a high incidence of type 2 diabetes or coronary artery disease in the general population. Paradoxically, serum adiponectin is elevated in patients with chronic kidney disease (CKD), such as overt diabetic nephropathy. The current study aimed to investigate whether anemia was independently associated with the serum level of high-molecular-weight (HMW) adiponectin in patients with type 2 diabetes. We studied 207 type 2 diabetic patients (92 women and 115 men). Anemia was defined as a hemoglobin (Hb) <13.0g/dL in men and <12.0g/dL in women according to the guidelines of the World Health Organization (WHO). Overt nephropathy (CKD) was defined as clinical proteinuria and /or estimated glomerular filtration rate (eGFR) lower than 60mL/min for more than 3 months. The diabetic patients were divided into 4 groups according to the presence or absence of anemia and/or CKD. Serum HMW adiponectin levels were measured by a sandwich enzyme-linked immunosorbent assay. In all 207 patients with type 2 diabetes, serum total and HMW adiponectin levels were correlated positively with age, the duration of diabetes, high-density lipoprotein (HDL) cholesterol, urinary albumin, and serum erythropoietin, whereas negative correlations were found with body mass index, triglyceride, eGFR, Hb, hematocrit, and high sensitivity C-reactive protein. A stepwise regression analysis demonstrated that among several significant variables, Hb had the strongest independent influence on HMW adiponectin (beta =-0.487, P < 0.001). Diabetic patients of both sexes with anemia and CKD had the highest serum levels of HMW adiponectin among the 4 groups. In conclusion, anemia is associated with marked elevation of serum HMW adiponectin levels in diabetic patients who have CKD, and this elevation is independent of renal function.

Serum high-molecular weight adiponectin decreases abruptly after an oral glucose load in subjects with normal glucose tolerance or impaired fasting glucose, but not those with impaired glucose tolerance or diabetes mellitus

Adiponectin exists in the blood as 3 forms, which are a trimer, a hexamer, and a high-molecular weight (HMW) form. We investigated whether circulating HMW adiponectin levels were altered by oral glucose or fat ingestion. Forty male subjects underwent a 75-g oral glucose loading test (OGTT), and 11 healthy subjects (5 women and 6 men) received a fat loading test. Serum levels of HMW and total adiponectin were measured during the OGTT and the fat loading test. The fat loading test was performed for at least 8 hours. Among the 40 male subjects, 11 had normal glucose tolerance (NGT), 9 had impaired fasting glucose (IFG), 11 had impaired glucose tolerance, and 9 had diabetes mellitus (DM). In all 40 subjects, the serum total adiponectin level did not change significantly, whereas serum HMW adiponectin decreased significantly after a glucose load and reached 92.2% of the basal level at 120 minutes after the OGTT (P < .01). The HMW to total adiponectin ratio decreased significantly from 0.47 +/- 0.15 at baseline to 0.43 +/- 0.13 at 120 minutes after a glucose load (P < .05). Serum HMW adiponectin measured at 120 minutes after the OGTT decreased significantly to 86.0% and 85.6% of the basal level in subjects with NGT or IFG, respectively (both P < .01). In subjects with impaired glucose tolerance or DM, however, serum HMW adiponectin did not change. The area under the curve for insulin at 30 minutes after a glucose load during the OGTT was significantly larger in subjects with NGT or IFG than in those with DM (P < .05). In addition, the insulinogenic index (DeltaI(0-30)/DeltaG(0-30)) was significantly higher in subjects with NGT or IFG than in those with DM (P < .001). Percentage changes in serum HMW adiponectin of the baseline at 120 minutes correlated negatively with those in serum insulin (r = -0.468, P = .0023), but not plasma glucose, of the baseline at 30 minutes in 40 subjects. On the other hand, serum triglycerides increased significantly after an oral fat load in 11 healthy subjects; but neither serum total nor HMW adiponectin changed. In conclusion, serum HMW adiponectin (but not total adiponectin) decreased rapidly after glucose loading in subjects with NGT or IFG; and the decrease of HMW adiponectin may be associated with an increase of serum insulin at 30 minutes.

Low-dose pioglitazone increases serum high molecular weight adiponectin and improves glycemic control in Japanese patients with poorly controlled type 2 diabetes

We investigated the effects of low-dose pioglitazone (7.5mg/day) on serum high molecular weight (HMW) adiponectin and fluid retention (estimated from hematocrit) in 14 male and 16 female patients with type 2 diabetes. All of them were being treated with sulfonylureas and had poor glycemic control. Patients were given 7.5 mg/day of pioglitazone and were followed for 12 weeks at monthly intervals. In all 30 patients, HbA1c was significantly decreased after 12 weeks of treatment with pioglitazone (8.2+/-0.7% vs. 7.4+/-0.8%, P<0.0001). Serum HMW adiponectin increased markedly from 5.2 (2.4, 8.6) microg/ml at baseline to 9.8 (4.1, 12.6) microg/ml at the end of pioglitazone treatment (P<0.0001). When the changes were evaluated separately for each sex, diabetic men showed no increase of body weight or BMI after treatment, while HbA1c decreased significantly, and did Hct. Serum HMW adiponectin increased significantly after treatment. In diabetic women, neither body weight nor BMI increased after treatment with pioglitazone, as was the case for the men. HbA1c decreased significantly, and did Hct. Serum HMW adiponectin increased significantly after treatment. In conclusion, low-dose pioglitazone therapy could significantly improved glycemic control and markedly increased serum HMW adiponectin in both male and female Japanese patients with type 2 diabetes.

Effects of losartan on serum total and high-molecular weight adiponectin concentrations in hypertensive patients with metabolic syndrome

High-molecular weight (HMW) adiponectin may have the most biologic activity among several isoforms. We investigated long-term effects of losartan on serum concentrations of total and HMW adiponectin in hypertensive patients with metabolic syndrome (MS) by serial measurements over 6 months. Forty hypertensive patients first received 50 mg of losartan. Upward titration of the losartan dose was implemented to reach a target blood pressure of less than 140/90 mm Hg. Serum total adiponectin and HMW adiponectin were measured at study entry (baseline), the 3-month treatment time point, and the end of the 6-month period. Non-HMW adiponectin (ie, medium- and low-molecular weight adiponectin) was calculated as total adiponectin--HMW adiponectin. Diagnosis of MS was done by current standard criteria. In hypertensive patients without MS (n = 21), the serum total adiponectin increased from 9.8 +/- 5.4 microg/mL at baseline to 11.1 +/- 6.2 microg/mL at 6 months (P < .01). Furthermore, the serum total adiponectin was significantly higher at 6 months than at 3 months (P < .01). Serum HMW adiponectin also increased from 5.7 +/- 3.9 microg/mL at baseline to 6.6 +/- 4.4 microg/mL at 6 months (P < .01). In hypertensive patients with MS, the serum total adiponectin increased from 6.0 +/- 2.7 mug/mL at baseline to 6.7 +/- 3.3 microg/mL at 3 months and to 7.0 +/- 3.1 microg/mL at 6 months (P < .01 for both). Furthermore, the serum HMW adiponectin concentration was significantly higher at 6 months than at 3 months (P < .001). However, the serum non-HMW adiponectin concentration did not change during treatment in either group. In conclusion, serum total and HMW adiponectin concentrations increase after 6 months of losartan treatment in hypertensive patients, irrespective of the presence or absence of MS.

Acarbose treatment increases serum total adiponectin levels in patients with type 2 diabetes

Adiponectin is an anti-diabetic and anti-atherogenic adipokine that serves as a major determinant of insulin sensitivity. Thiazolidine derivatives increase circulating adiponectin, particularly the high molecular weight isoform, which has been shown to well correlate with amelioration of insulin resistance by thiazolidines in diabetic patients. alpha-glucosidase inhibitors are another class of anti-diabetic agents that specifically reduce postprandial blood glucose elevations, but its effect on adiponectin is largely unknown. In the present study we investigated effect of an alpha-glucosidase inhibitor, acarbose, together with pioglitazone, the only thiazolidine derivative available in Japan, on serum concentrations of adiponectin. Seventeen patients with type 2 diabetes were treated with acarbose and sixteen with pioglitazone for three months. Treatment with acarbose and pioglitazone decreased HbA1c values by 0.49% and 0.63%, respectively. Pioglitazone, as expected, increased serum levels of total adiponectin by 2.1 fold and its high molecular weight isoform by 3.6 fold. We found that acarbose also caused a small but significant increase in serum concentrations of total adiponectin. However, in contrast to pioglitazone, no appreciable changes were observed in the levels of high molecular weight adiponectin. In conclusion, acarbose increases serum concentrations of total adiponectin without preference of the high molecular weight isoform in type 2 diabetic patients. Clinical relevance of the increased adiponectin to the acarbose effects remains to be elucidated.

Performance of ELISA for specific measurement of high-molecular-weight (HMW) adiponectin

Adiponectin is an adipocyte-specific protein secreted as trimer, hexamer and high-molecular-weight (HMW) complex. Several reports have indicated that the biologically active form of adiponectin is HMW, and that HMW adiponectin concentration is correlated with insulin sensitivity and metabolic disorders including diabetes better than total adiponectin concentration. We developed a sandwich ELISA using a monoclonal antibody against HMW adiponectin purified from human serum. The specificity of established ELISA to HMW adiponectin was confirmed by analysis of human serum fractions prepared by gel filtration chromatography. After careful purification of HMW adiponectin for the calibration standard, the concentration was determined by the amino acid analysis, protein concentration assay by Lowry's method and theoretical calculation from amino acid sequence of adiponectin. An appropriate calibration curve was obtained by HMW adiponectin standards and an assay range is from 0.2 to 25 ng/mL. Intra- and inter-assay coefficient of variation (CV) was below 3.0% and 5.1%, respectively. The recovery of added HMW adiponectin was from 98.5% to 99.2%. No interference of blood components was confirmed by adding free and conjugated forms of bilirubin, hemoglobin and lipids. Serum is suitable as samples and could be stored at 10 degrees C in the refrigerator for at least 28 days stably. Our HMW adiponectin-specific ELISA system is simple, without any procedure of sample pretreatment, reliable, suitable for routine analysis and highly useful for elucidating the clinical significance of adiponectin.