Serum glycerophosphate levels are increased in Japanese men with type 2 diabetes.

OBJECTIVE: To identify metabolites showing changes in serum levels among Japanese male with diabetes. METHODS: We performed metabolite profiling by coupling capillary electrophoresis with electrospray ionization time-of-flight mass spectrometry using fasting serum samples from Japanese male subjects with diabetes (n=17), impaired glucose tolerance (IGT; n=5) and normal glucose tolerance (NGT; n=14). RESULTS: Other than the expected differences in characteristics related to abnormal glucose metabolism, the percent body fat was significantly different among subjects with diabetes, IGT and NGT (27.3±6.2, 22.2±4.5 and 19.2±6.0%, respectively, p=0.0022). Therefore, percent body fat was considered as a possible confounding factor in subsequent analyses. Of 560 metabolites detected using our platform, the levels of 74 metabolites were quantified in all of the serum samples. Significant differences between diabetes and NGT were observed for 24 metabolites. The top-ranked metabolite was glycerol-3-phophate (glycerophosphate), which was significantly higher in subjects with diabetes than in those with NGT, even after Bonferroni correction for multiple testing (11.7±3.6 vs. 6.4±1.9 µM, respectively; corrected p=0.0222). Stepwise multiple regression analyses revealed that serum glycerophosphate levels were significantly correlated with 2-h plasma glucose after a 75-g oral glucose tolerance test (r=0.553, p=0.0005), independently of other characteristics, including FPG and HbA1c. CONCLUSION: Serum glycerophosphate levels were found to be elevated in Japanese men with diabetes, and correlated with 2-h PG, independent of FPG and HbA1c. Namely, serum glycerophosphate level at fasting condition can be a marker for predicting glucose intolerance. These results warrant further studies to evaluate the relevance of glycerophosphate in the pathophysiology of diabetes.

Higher plasma renin activity is a risk factor for total mortality in older Japanese individuals: the Takahata study.

Plasma renin activity (PRA) is accepted as a marker for increased risk of cardiovascular diseases. However, the association between PRA and total mortality has not been fully explored in a general population. We here examined whether PRA is associated with increased total mortality in a general Japanese population. The participants of the Takahata study (3502 subjects; age, 62.5 ± 10.4 years), a population-based, longitudinal study of Japanese held from 2004 to 2006, were enrolled and followed up for up to 7 years. The incidence of death and causes of death were monitored annually to the end of 2010 (median follow-up, 2280 days). During the follow-up period, 143 subjects died. Kaplan-Meier analysis showed a significantly increased risk for total mortality in subjects with higher PRA (log-rank P < .001). Cox proportional hazard model analyses with adjustment for factors correlated with PRA (age, sex, weight, diastolic blood pressure, high-density lipoprotein cholesterol, uric acid, B-type natriuretic peptide, serum total protein, antihypertensive treatment, and diabetes) showed that higher PRA was associated with increased total mortality in linear regression models (per 1 increase in log 10 × PRA [nanograms per milliliter per hour]: hazard ratio, 2.12; 95% confidence interval, 1.47-3.06), between groups of patients stratified by quartiles of PRA (highest vs lowest quartile: 2.63, 1.57-4.41) and in subjects with high (≥ 2.0 ng/[mL h]) vs low (<2.0 ng/[mL h]) PRA (1.97, 1.37-2.83). Higher PRA was a significant and independent risk factor for increased total mortality in this Japanese population and may be a marker for subjects at an increased risk of total mortality.

Association of the clusterin gene polymorphisms with type 2 diabetes mellitus.

The association of the clusterin (CLU) gene polymorphism (single nucleotide polymorphisms [SNPs] 1-4: rs1532278, rs1532277, rs2279590, and rs2279591, respectively) with type 2 diabetes mellitus was examined using a population of the Funagata study (n [male-female] = 1631 [741:884]; age, 62.0 ± 12.1 years), a Japanese community-based study. Single nucleotide polymorphisms 1 to 3 were significantly associated with hemoglobin A(1c) levels (P = .0154, .0021, and .0006, respectively) and diabetes (.0310, .0170, and .0021, respectively). A case-control association study of SNP 3 with diabetes by multiple logistic regression analysis showed a significant association of genotype AA (the at-risk genotype) with an odds ratio (OR) of 2.33 (P = .0039) independently of age and sex. The association was marginally validated by a study with another Japanese community-based sample, the Takahata Study (n [male-female] = 2.948 [1333:1615]; age, 63.0 ± 10.2 years) (OR, 1.59; P = .0595; χ(2)P = .0264). When the 2 samples were combined, the association became more significant (OR, 1.75; P = .0025). In subjects with the non-at-risk genotypes, the insulin resistance index--homeostasis model assessment of insulin resistance (HOMA-R)--increased significantly (P < .0001) and the insulin secretion index--HOMA-ß--appeared to decrease (P = .1803 and .0097, respectively, for the genotypes AG and GG) as the glucose tolerance progressed toward diabetes (normal glucose tolerance to glucose intolerance to diabetes). However, in subjects with the at-risk genotype, HOMA-R and HOMA-ß showed a significant increase already in the subjects with normal glucose tolerance (P = .0239 and .0305, respectively); and as the glucose tolerance progressed toward diabetes, HOMA-R stayed approximately the same, whereas HOMA-ß decreased significantly (P = .0332). The CLU gene was associated with diabetes, probably through an increase in insulin resistance primarily and through an impairment of insulin secretion secondarily.

Association of the Ser326Cys polymorphism in the OGG1 gene with type 2 DM.

The association of the Ser326Cys polymorphism of the 8-oxoguanine glycosylase 1 (OGG1) gene with type 2 diabetes was examined using a Japanese population (n (M/W): 4585 (2085/2500); age: 62.6 +/- 10.9 years). HbA1c levels and frequency of diabetic subjects were significantly higher in subjects with genotypes with Cys allele than in those without (p = 0.032 and 0.037, respectively). Multiple logistic regression analysis showed that genotypes with Cys allele were significantly associated with diabetes (OR: 1.32, p = 0.0289). In subjects whose glucose tolerance was classified by FPG and 2-h PG (n = 1.634), the association was more substantial (genotypes with Cys allele vs. without, OR: 1.70, p = 0.0059; genotypes Cys/Cys vs. Ser/Ser, OR: 2.19, p = 0.0008). In subjects with genotype Ser/Ser, the insulin secretion index, HOMA-beta, increased in the subjects with glucose intolerance and decreased in the subjects with diabetes, while, in subjects with genotypes Ser/Cys + Cys/Cys, HOMA-beta decreased as the glucose tolerance progressed (p for trend = 0.010).

Salt consumption-dependent association of the GNB3 gene polymorphism with type 2 DM.

The associations of the C825T polymorphism (rs5443) of the G-protein beta3 subunit (GNB3) gene and eight adjacent single nucleotide polymorphisms (SNPs) with diabetes were examined using a Japanese population (n (M/W): 2956 (1335/1621); age: 63.0+/-10.2 years). Fasting plasma glucose (FPG) levels were significantly associated with the C825T polymorphism and two flanking SNPs (rs2301339 and rs5446) (p=0.002, 0.001, and 0.008, respectively). A case-control association study of the C825T polymorphism with diabetes using multiple logistic regression analysis showed a significant association of the genotypes TT+TC with an odds ratio of 0.62 (p=0.008) independent of age, gender, and BMI. The effects of salt consumption on the association were then examined (n=1635). The FPG levels were significantly associated with the C825T polymorphism only in subjects with low salt consumption (<12.44 g/day) (p=0.002). A case-control association study also showed a significant association with diabetes only in subjects with low salt consumption (p=0.006).

Ghrelin infused into the portal vein inhibits glucose-stimulated insulin secretion in Wistar rats.

Although accumulating evidence has shown crucial roles of ghrelin and insulin in food intake and energy metabolism, the exact relationship between these hormones remains unclear. In this study, we determined the in vivo effect of ghrelin on insulin secretion. We demonstrated that ghrelin inhibited the glucose-stimulated release of insulin when infused into the portal vein of Wistar rats. However, ghrelin infusion into the femoral vein did not induce such an inhibitory effect. Hepatic vagotomy or coinfusion with atropine methyl bromide diminished the inhibitory effect of ghrelin on glucose-stimulated insulin secretion. In conclusion, ghrelin exerts an inhibitory effect on glucose-stimulated insulin secretion via the hepatic portal system and the vagus nerve. The decrease in ghrelin level after a meal is important for the occurrence of the incretin effect in rats.

A functional polymorphism of the TNF-alpha gene that is associated with type 2 DM.

To examine the association of the tumor necrosis factor-alpha (TNF-alpha) gene region with type 2 diabetes (DM), 11 single-nucleotide polymorphisms (SNPs) of the region were analyzed. The initial study using a sample set (148 cases vs. 227 controls) showed a significant association of the SNP IVS1G+123A of the TNF-alpha gene with DM (p=0.0056). Multiple logistic regression analysis using an enlarged sample set (225 vs. 716) revealed the significant association of the SNP with DM independently of any clinical traits examined (OR: 1.49, p=0.014). The functional relevance of the SNP were examined by the electrophoretic mobility shift assays using nuclear extracts from the U937 and NIH3T3 cells and luciferase assays in these cells with Simian virus 40 promoter- and TNF-alpha promoter-reporter gene constructs. The functional analyses showed that YY1 transcription factor bound allele-specifically to the SNP region and, the IVS1+123A allele had an increase in luciferase expression compared with the G allele.

Pioglitazone reduces atherogenic outcomes in type 2 diabetic patients.

AIM: The aim of this study was to evaluate the anti-atherogenic outcomes of pioglitazone, a thiazolidinedione derivative, in type 2 diabetic patients. METHODS: Eight patients with poor diabetic control were treated with 15 mg of pioglitazone for 4 months. Blood samples were collected monthly, and the levels of fasting plasma glucose (FPG), HbA1c, and lipids, such as triglycerides, total cholesterol, low-density lipoprotein-cholesterol, and high-density lipoprotein-cholesterol, were measured. Other parameters, including immunorecative insulin (IRI), remnant-like particle-cholesterol (RLP-C), adiponectin, plasminogen activator inhibitor type 1 (PAI-1), tumor necrosis factor (TNF)- alpha , leptin, brain natriuretic peptide (BNP), and high-sensitivity (hs)-C-reactive protein (CRP), were examined at the beginning and end of the study. In addition, clinically adverse side-effects were evaluated. RESULTS: Treatment with pioglitazone significantly decreased the levels of HbA1c, FPG, the homeostasis model assessment of insulin resistance (HOMA-IR) index, RLP-C, PAI-1, TNF- alpha , and hs-CRP, but not the level, IRI, lipids, or leptin. In contrast, adverse side-effects, including body weight gain, liver dysfunction and edema, were not observed during this study. CONCLUSION: These results strongly suggested that treatment with pioglitazone has a greater clinical benefit for the prevention of atherosclerosis, including coronary heart diseases, without any adverse side-effects.

Impaired glucose tolerance is a risk factor for stroke in a Japanese sample--the Funagata study.

Impaired glucose tolerance (IGT) is a known risk factor for cardiovascular disease, which includes stroke as well as coronary heart disease (CHD). We investigated whether IGT is a risk factor for stroke. The incidence of stroke and CHD in a cohort population (n = 2938) consisting of participants of the 1990-1997 Funagata study was assessed through interviews with the participants and their family members and reviews of death certificates and residence transfer documents through 2002. Glucose tolerance at the baseline was classified according to the criteria of the 1998 World Health Organization (normal glucose tolerance, n = 2189; IGT, n = 320; and diabetes, n = 286). The cumulative incidences among the groups were compared using the Kaplan-Meier product-limit method, and the risks of these conditions were evaluated by person-year and Cox proportional hazard methods. During the 147-month (mean, 116.5 months) follow-up, 158 (normal glucose tolerance, IGT, and diabetes: 94, 35, and 29, respectively) participants experienced a stroke and 94 (54, 16, and 24, respectively) experienced CHD. By the person-year method, IGT and diabetes were shown to be significant risk factors for stroke and CHD (odds ratio, 1.87 [95% confidence interval, 1.73-2.03] and 3.57 [3.21-3.98] for stroke; 1.53 [1.31-1.78] and 3.47 [2.91-4.14] for CHD, respectively). Cox proportional hazard analysis showed that IGT was a risk factor for stroke (age-, sex-, and hypertension-adjusted hazard ratio: 1.51 [95% confidence interval, 1.02-2.24], P = .039) but not for CHD (1.21 [0.69-2.313], .509). Impaired glucose tolerance is a risk factor for future stroke in a Japanese population.

Association of the PIK3C2G gene polymorphisms with type 2 DM in a Japanese population.

The associations of five SNPs (SNPs1-5: A-5468G, A-3333G, C-1794T, C437T and T9148C) of the class II phosphoinositide 3-kinase gamma-subunit (PIK3C2G) gene with type 2 diabetes were examined using a population of the Takahata Study (n (M/W): 2930 (1328/1602); age: 63.3+/-10.2 years), a Japanese community-based study. Quantitative association study of the SNPs with HbA1c levels showed significant association for SNPs 2 and 4 (p=0.018 and 0.004, respectively). A case-control association study of SNP 4 with diabetes by multiple logistic regression analysis showed a significant association of the genotype TT of the SNP with an odds ratio of 2.21 (p=0.001) independently of age, gender and BMI. In the NGT subjects, serum fasting insulin levels in the at-risk genotype group of SNP 4 were significantly lower than those in the others (TT, TC, and CC, 4.9+/-2.6, 5.4+/-3.0, and 5.6+/-3.4muU/ml, respectively; p=0.029).

Characterization of activation of MAP kinase superfamily in vasculature from diabetic rats.

AIM: This study was investigated to characterize the activation mechanism of a mitogen-activated protein (MAP) kinase superfamily in diabetes in aortae and cultured vascular smooth muscle cells (VSMCs) from rats. METHODS: Male Sprague-Dawley rats were used for this procedure, and diabetes was induced by streptozotocin injection at 50 mg/kg. After 6 weeks, the thoracic aortae from normal and diabetic rats were removed for detection of the MAP kinase superfamily by immunoblot analysis. RESULTS: In aortae, the protein levels of extracellular signal-regulated protein kinase (ERK)-1, c-jun NH2-terminal protein kinase (JNK)-1 and -2, and p38 increased significantly more in diabetic rats than in normal rats. In contrast, phosphorylated protein levels of ERK-1 and -2, JNK-1, and p38 were significantly more elevated in diabetic rats than in normal rats. In VSMCs from normal rats, a high concentration of glucose cultured for three days significantly increased the phosphorylated protein levels of ERKs and p38, but not JNKs, without any change of these protein levels. Serum interleukin (IL)-1beta was significantly higher in diabetic rats than in normal rats. Several types of proinflammatory cytokine dose-dependently phosphorylated the levels of ERKs, JNK-1, and p38, but not JNK-2, in VSMCs from normal rats. In cells from diabetic rats, phosphorylated protein levels of ERKs and p38 were significantly elevated by IL-1beta. In addition, interferon-gamma phosphorylated the levels of ERKs in diabetic cells more than in normal cells. CONCLUSION: Our results suggest that, under diabetic conditions, the MAP kinase superfamily was activated by different pathways in the vasculature; i.e., ERKs and p38 might be mainly phosphorylated by a complex of high concentrations of glucose and of several types of proinflammatory cytokines, but the phosphorylation of JNK-1 might depend on the concentration of proinflammatory cytokines such as IL-1beta, and/or additional unknown factors, except glucose.

A palatinose-based balanced formula improves glucose tolerance, serum free fatty acid levels and body fat composition.

Palatinose is a disaccharide present in honey, which has the characteristics of delayed digestion and absorption. We developed a palatinose-based balanced formula (PBF) and reported its beneficial effects on metabolic syndrome-related parameters in rats. To examine the effects of PBF in humans, we here conducted a crossover study using twenty-three subjects with impaired glucose tolerance. The subjects were divided into two groups: intervention to control (I/C) and control to intervention (C/I) groups. The I/C group consumed PBF (250 kcal) together with foods that were 250 kcal less than their usual breakfast (intervention meal) for the first 12 weeks, followed by their usual breakfast (control meal) for the last 12 weeks. The protocol for the C/I group was opposite in order: the control meal for the first 12 weeks, followed by the intervention meal for the last 12 weeks. In the first 12-week period, the intervention meal decreased 2-hr plasma glucose levels after 75-g oral glucose tolerance test (-15.7 +/- 20.1% change), while the control meal did not (0.8 +/- 31.6% change). The difference between these changes was significant (p = 0.038). The similar results were obtained from the comparison of the changes between the first and the last 12-week periods in the two groups combined (intervention vs control: -11.8 +/- 22.5 vs 11.2 +/- 30.2% change, p = 0.024). PBF also had the beneficial effects on serum free fatty acids levels and visceral fat area. In conclusion, PBF consumption has beneficial effects on metabolic syndrome-related parameters in humans.

Effect of pioglitazone on atherogenic outcomes in type 2 diabetic patients: a comparison of responders and non-responders.

The aim of this study was to evaluate the anti-atherogenic efficacy of pioglitazone, a thiazolidinedione derivative, on the change in atherogenic outcomes by comparing responder and non-responder groups in type 2 diabetic patients. Twenty-three patients with poor diabetic control were treated with 15 mg of pioglitazone for 12 months. The levels of fasting plasma glucose (FPG), HbA1c, triglycerides (TG), total cholesterol (T-Cho), low-density lipoprotein-cholesterol (LDL-C), and high-density lipoprotein-cholesterol (HDL-C) were measured monthly, and those of remnant-like particle-cholesterol (RLP-C) and lipoprotein (a) [Lp (a)] were measured every 3 months. In Month 6, the patients were divided into two groups according to the decrease in HbA1c level: the responder group showed a decrease of > or =1%; the non-responder group, a decrease of <1%. In the responder group, the levels of FPG and HbA1c decreased significantly after Month 3. The values of the body mass index (BMI), homeostasis model assessment of insulin resistance (HOMA-IR) index, LDL-C, and RLP-C were significantly higher in the responder group than in the non-responder group. Although the levels of T-Cho and HDL-C were unchanged in both groups, those of TG and RLP-C were drastically reduced in the responder group. Interestingly, the relative change in Lp (a) was significantly decreased in both groups. These results strongly suggest that pioglitazone is beneficial for type 2 diabetic patients with high levels of BMI, HOMA-IR, LDL-C, and RLP-C, as it helps to prevent the progression of atherosclerosis, including coronary heart diseases.

Correlation between change in body weight rather than current body weight and change in serum adiponectin levels in a Japanese population -- the Funagata study.

Serum adiponectin levels are decreased in obese subjects. We examined the association of current body weight (BW) and its change with a change in serum adiponectin levels. Serum adiponectin levels at the baseline (from 1995 to 1997) and the 5-year follow-up (from 2000 to 2002) examinations were evaluated in 1003 (M/F, 425/578; age at the baseline examinations, 58.3 +/- 11.7/57.5 +/- 11.0 years) Japanese subjects from a cohort population (N = 2013) of the Funagata study. Correlations and associations of BW at the baseline examinations and changes in BW between the baseline and the follow-up examinations (deltaBW) with changes in the serum adiponectin levels in the study period (deltaAdiponectin) were examined. Stepwise regression analyses revealed a significant correlation of the deltaBW (r = -0.233 and -0.204 for men and women, respectively; r = -0.324 for the upper tertile group divided based on their body mass index in women) with the deltaAdiponectin. However, the BW at the baseline examinations was not significantly correlated in both sexes. Multiple logistic regression analyses revealed that subjects who reduced their BW by 2 kg or more were 2.56 (95% confidence interval, 1.21-5.42; P = .014) and 8.24 times (95% confidence interval, 3.59-18.9; P < .001) more likely to be in the upper tertile of the deltaAdiponectin than those who increased their BW by 2 kg or more in men and women, respectively, independent of their BW at the baseline examinations. In conclusion, we showed here that the deltaBW was strongly associated with the deltaAdiponectin in both sexes, whereas the BW at the baseline examinations was not associated with the deltaAdiponectin, at least in women.

Characterization of plasma brain natriuretic peptide level in patients with type 2 diabetes.

This study investigates whether the plasma brain natriuretic peptide (BNP) level is increased by the clinical traits of diabetes, including its complications, and whether these levels are affected by the presence of other combined diseases such as hypertension, hyperlipidemia, and coronary heart disease (CHD) in patients with diabetes. In 223 patients with Type 2 diabetes, the mean value of plasma BNP reached 32.3+/-4.1 pg/mL. The levels significantly increased with age, hypertension, and CHD but not with the duration of diabetes, HbA1c level, or hyperlipidemia. With regard to the type of therapy, the BNP levels were significantly lower in the combinations of both sulfonylurea and metformin and sulfonylurea and pioglitazone than those in insulin alone. In addition, the BNP levels in the group with diabetic complications, including retinopathy and nephropathy, and macroalbuminuria were significantly elevated in comparison with those without these complications and macroalbuminuria. Interestingly, however, no difference was observed between these groups after removal of the values in patients with CHD. These results have clarified that the plasma BNP levels in diabetic patients could increase only by the progression of macrovascular diseases, such as CHD, but not by the current diabetic control or diabetic microvascular complications.

Association of decrease in serum dehydroepiandrosterone sulfate levels with the progression to type 2 diabetes in men of a Japanese population: the Funagata Study.

Association of serum dehydroepiandrosterone sulfate (DHEAS) levels with insulin resistance and impairment of insulin secretion have been reported. We here examined the association of serum DHEAS levels with type 2 diabetes mellitus (DM) and the progression to DM. The serum DHEAS levels at baseline (from 1995 to 1997) were evaluated in 1709 individuals (998 women and 711 men) from a cohort population (n = 3706) of the Funagata Study. Glucose tolerance was evaluated at baseline as well as at 5-year follow-up examinations (n = 970, follow-up rate, 56.8%) according to the 1985 World Health Organization criteria. The statistical significance of the difference between any 2 groups was determined by the Student t test. Multiple logistic regression analysis determined the association of the traits with the progression to DM at the 5-year follow-up examinations. P < .05 was accepted as statistically significant. The serum DHEAS levels were significantly lower in DM than in normal glucose tolerance. However, this difference was not significant when adjusted for age. In men, the decrease in serum DHEAS levels by the 5-year follow-up examinations was significantly larger in the subjects who became diabetic than in the subjects who remained normal glucose tolerance, even when adjusted for age ( P = .0003). Multiple logistic regression analysis revealed a significant association of the decrease in serum DHEAS levels with the progression to DM, with an odds ratio (per 0.1 log ng/mL) of 1.410 (95% confidence interval [CI], 1.020-1.948, P = .038), independently from age, height, and 2-hour plasma glucose in men. A decrease in serum DHEAS levels seems to be associated with the progression to DM in Japanese men.

Association of the ABCA1 gene polymorphisms with type 2 DM in a Japanese population.

To examine the association of the ATP-binding cassette transporter 1 (ABCA1) gene with type 2 diabetes (DM), we studied genetic polymorphisms of the ABCA1 gene including its linkage disequilibrium (LD) and haplotype analyses using a Japanese population. A sample set (DM:72, IGT:75, and NGT:227) was genotyped with 34 SNPs distributed from the promoter region to the last exon of the ABCA1 gene. LD between SNPs was assessed in pairwise manner. Among 13 LD blocks constructed, an LD block at the 5'-region showed a significant difference in the haplotype distribution between the study groups (NGT vs. IGT + DM: overall p = 0.0180; NGT vs. DM: 0.0001). Fisher's exact probability test (NGT vs. DM) showed a significant association of the haplotype 2 of the LD block (p = 0.0001), with an odds ratio (OR) of 2.53 (95%CI:1.62-4.12). Diplotype analysis also showed a significant association of the diplotypes with the haplotype 2 (OR:2.59, 95%CI:1.48-4.54, p = 0.0013).

Progression of diabetic nephropathy enhances the plasma osteopontin level in type 2 diabetic patients.

Osteopontin (OPN) is thought to play multiple roles in the progression of atherosclerotic plaque including diabetic vascular complications. However, it still remains unclear whether the level of OPN in vivo is indeed clinically associated with the progression of diabetic complications. This study evaluated whether the levels of OPN in plasma and urine are correlated with the progression of diabetic complications, such as retinopathy, neuropathy, and nephropathy in patients with type 2 diabetes. In 229 patients with type 2 diabetes, OPN level in plasma and urine was evaluated by both the severity of diabetic complications, such as retinopathy, neuropathy, and nephropathy, and the clinical characteristics and the substantial laboratory findings. Plasma OPN level increased significantly with aging and the progression of diabetic nephropathy, especially at the stage of renal failure (p<0.05). However, the level was not related to the progression of retinopathy or neuropathy, or to laboratory findings, such as HbA1c or serum lipids. In contrast, urinary OPN level was not associated with diabetic complications in any of the subjects. There was no correlation between the plasma and urinary values of OPN. The results established that the plasma OPN was elevated in proportion to the progression of diabetic nephropathy, indicating that the plasma concentration may be a potential diagnostic predictor of diabetic end-stage renal disease.