Serum uric acid and disorders of glucose metabolism: the role of glycosuria

Uric acid and diabetes mellitus: an update

The relationship between diabetes mellitus (DM) and high serum uric acid is complex and controversial. Many epidemiological studies have reported a positive association, whereas others have reported an inverse association or none. In the pathogenesis of DM it is the intracellular urate that is more important than the extracellular and dissociation between the two is possible. Evidence suggests that high serum uric acid induces insulin resistance and beta cell failure in animal models. Reduction of intracellular uric acid can be achieved by dietary measures such as reducing fructose and salt intake, and uric acid-lowering drugs. We suggest that in the Western diet, these elements play a crucial role in pathogenesis of DM. To determine the precise and exact interrelationship between intracellular and extracellular uric acid, well-designed studies are required. Besides this, clinical trials are needed to determine whether intracellular and extracellular urate reduction will provide benefit in prevention and treatment of DM and complications associated with it.

Metabolic Syndrome and Its Components Are Associated with New-Onset Hyperuricemia in a Large Taiwanese Population Follow-Up Study

The prevalence rate of hyperuricemia remains high in Taiwan, at 21.6% in men and 9.57% in women. Both metabolic syndrome (MetS) and hyperuricemia can cause many complications; however, few studies have evaluated the correlation between MetS and hyperuricemia. Therefore, in this observational cohort study, we explored associations between metabolic syndrome (MetS) and its components and new-onset hyperuricemia. Of 27,033 individuals in the Taiwan Biobank who had complete follow-up data, we excluded those with hyperuricemia at baseline (n = 4871), those with gout at baseline (n = 1043), those with no data on baseline uric acid (n = 18), and those with no data on follow-up uric acid (n = 71). The remaining 21,030 participants (mean age 50.8 ± 10.3 years) were enrolled. We found a significant association between new-onset hyperuricemia with MetS and the components of MetS (hypertriglyceridemia, abdominal obesity, low high-density lipoprotein cholesterol, hyperglycemia, and high blood pressure). Furthermore, compared to those without any MetS components, those with one MetS component (OR = 1.816), two MetS components (OR = 2.727), three MetS components (OR = 3.208), four MetS components (OR = 4.256), and five MetS components (OR = 5.282) were significantly associated with new-onset hyperuricemia (all p < 0.001). MetS and its five components were associated with new-onset hyperuricemia in the enrolled participants. Further, an increase in the number of MetS components was associated with an increase in the incidence rate of new-onset hyperuricemia.

Prediction model of random forest for the risk of hyperuricemia in a Chinese basic health checkup test

Objectives: The present study aimed to develop a random forest (RF) based prediction model for hyperuricemia (HUA) and compare its performance with the conventional logistic regression (LR) model. Methods: This cross-sectional study recruited 91,690 participants (14,032 with HUA, 77,658 without HUA). We constructed a RF-based prediction model in the training sets and evaluated it in the validation sets. Performance of the RF model was compared with the LR model by receiver operating characteristic (ROC) curve analysis. Results: The sensitivity and specificity of the RF models were 0.702 and 0.650 in males, 0.767 and 0.721 in females. The positive predictive value (PPV) and negative predictive value (NPV) were 0.372 and 0.881 in males, 0.159 and 0.978 in females. AUC of the RF models was 0.739 (0.728–0.750) in males and 0.818 (0.799–0.837) in females. AUC of the LR models were 0.730 (0.718–0.741) for males and 0.815 (0.795–0.835) for females. The predictive power of RF was slightly higher than that of LR, but was not statistically significant in females (Delong tests, P=0.0015 for males, P=0.5415 for females). Conclusion: Compared with LR, the good performance in HUA status prediction and the tolerance of features associations or interactions showed great potential of RF in further application. A prospective cohort is necessary for HUA developing prediction. People with high risk factors should be encouraged to actively control to reduce the probability of developing HUA.

Metabolomic perturbation precedes glycolytic dysfunction and procreates hyperglycemia in a rat model due to bisphenol S exposure

Previous studies highlighted bisphenol S (BPS), an industrial chemical responsible for harmful effects comparable to its congener substance bisphenol A (BPA). Accounted for various adversities to biological functions, it could alter the expression of endogenous metabolites in many metabolic processes. The study was aimed to investigate the altered metabolites in hyperglycemic condition triggered by sub-chronic exposure of BPS in serum and urine samples of Wistar rats. Invaded effects of hyperglycemia due to BPS exposure on Wistar rats were investigated by oral glucose tolerance test (OGTT) and insulin tolerance test (ITT). Metabolomic profiling of serum and urinary metabolites was done by gas chromatography-mass spectrometry (GC-MS) analysis. The metabolomics data were represented by one way ANOVA, principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA) along with the mapping of perturbed metabolic pathways. The OGTT and ITT showed increased levels of glucose in treated animals with median and high doses, indicating the manifestation of hyperglycemia. The metabolomic profiling of serum and urine revealed BPS could cause consequential metabolomic perturbation mainly of amino acids, sugars, and organic acids. Furthermore, the extrapolation of Kyoto Encyclopedia of Genes and Genomes (KEGG) based systematic analysis helped to monitor the altered pathways, including amino acids, glycolysis, pyruvate metabolism, etc., which were provoked due to BPS exposure. The overview of the perturbed metabolite profiling in rats promisingly showed early diagnostic markers of hyperglycemic condition triggered due to the BPS exposure. Findings from this study will be helpful towards the exploration of mechanistic insights of several disturbed pathways.

Metabolic Syndrome and 5-Year Incident Hyperuricemia Among Older Chinese Adults: A Community-Based Cohort Study

BACKGROUND

There was a lack of studies focusing on older adults about the longitudinal association between metabolic syndrome (MetS) and hyperuricemia (HUA). We aimed to assess the association of baseline MetS and incident HUA among older Chinese adults, with a special focus on the associations between different combinations of MetS components and HUA.

METHODS

Data of 3247 Chinese adults aged 60 years or older included in a community-based longitudinal cohort study were analyzed. Anthropometric examinations and collection of blood sample were conducted both at baseline and follow-up. HUA was defined as 7 mg/dl or above for men and 6 mg/dl or greater for women. MetS was assessed based on the National Cholesterol Education Program-Adult Treatment Panel III, and older adults with the presence of at least three of MetS components were considered as having MetS.

RESULTS

MetS and its components, including high blood pressure (BP), high body mass index, diabetes mellitus and high triglycerides, were significantly related to incident HUA. The association between high BP and incident HUA is strongest among the five MetS components. Among all combinations of MetS components, the group consisting of diabetes mellitus, high BP and high triglycerides had the highest odds for incident HUA (OR = 13.07, 95% CI = 4.95-34.54).

CONCLUSION

MetS and its components, except for low high-density lipoprotein cholesterol, could increase the risk of HUA among community-dwelling older adults, and high BP may be the most important determinant.

Association of Serum Uric Acid with Metabolic Syndrome and Its Components: A Cross-Sectional Study in Chinese Coastal Population

Objective: Few studies reported the association between serum uric acid and the prevalence of metabolic syndrome in China's coastal residents. We aimed to examine the association between serum uric acid and the prevalence of metabolic syndrome as well as its components in adults and elderly from Shenzhen (a China's coastal city). Methods: We conducted a survey in a community-based household population in Shenzhen, collecting data about 4049 participants aged 20-69 years. Based on the data, we determined the prevalence of metabolic syndrome in adults and elderly with different serum uric acid concentrations. Results: According to the revised National Cholesterol Education Program Adult Treatment Panel III, the prevalence of the metabolic syndrome in the surveyed participants was 24.69% [95% confidence interval (CI): 23.4%-26.0%]. The prevalence of metabolic syndrome in participants with serum uric acid levels <4, 4-4.9, 5-5.9, 6-6.9, 7-7.9, and ≥8 mg/dL is 10.12% (95% CI: 8.2%-12.0%), 17.92% (95% CI: 15.8%-20.1%), 31.05% (95% CI: 28.1%-34.0%), 39.47% (95% CI: 35.4%-43.8%), 49.39% (95% CI: 43.1%-55.7%), and 52.57% (95% CI: 42.5%-62.5%), respectively. Multivariable logistic regression analysis showed that participants with higher serum uric acid levels were at a higher risk of high triglycerides, low high-density lipoprotein, central obesity, high blood pressure, or high fasting glucose (P < 0.001). Conclusions: Serum uric acid levels were closely associated with metabolic syndrome and its components in Chinese coastal population.

Differences in the association between glycemia and uric acid levels in diabetic and non-diabetic populations

AIMS

Our study aimed to investigate the influence of different glycemic statuses and their fasting plasma glucose/2-hour post-load glucose on uric acid level.

METHODS

A total of 14,787 subjects were recruited after excluding subjects with medication for hyperuricemia or diabetes. Fasting plasma glucose (FPG), 2-hour post-load glucose (2hPG), and uric acid (UA) were measured. Then, subjects were divided into normal glucose tolerance (NGT), impaired fasting glucose (IFG), impaired glucose tolerance (IGT), and diabetes.

RESULTS

After adjustment for clinical variables, in NGT group, there was no significant relationship found between UA level and FPG. However, there was a positive association between UA level and 2hPG (β = 0.003, 95% CI: 0.002~0.004). A similar trend was also observed between UA level and 2hPG in IFG group (β = 0.004, 95% CI: 0.000~0.009) and IGT group (β = 0.005, 95% CI: 0.002~0.008), but relationship between UA level and FPG remained insignificant. In diabetes group, UA level was negatively associated with both FPG (β = -0.008, 95% CI: -0.010 ~ -0.007) and 2hPG (β = -0.005, 95% CI: -0.006 ~-0.003).

CONCLUSIONS

In non-diabetic individuals, UA level increased with 2hPG, but not with FPG, and UA level was inversely associated with both FPG and 2hPG in diabetic population.

Increased urinary glucose excretion is associated with a reduced risk of hyperuricaemia

AIM

To investigate the association of urinary glucose excretion with levels of serum uric acid in adults with newly diagnosed diabetes.

METHODS

A total of 597 people with newly diagnosed diabetes, confirmed in an oral glucose tolerance test, were included in the present study. The participants were divided into two groups: 142 participants with low urinary glucose excretion and 455 with high urinary glucose excretion. Demographic characteristics and clinical variables were evaluated. The association of urinary glucose excretion with uric acid was analysed using multivariable regression analysis.

RESULTS

The low urinary glucose excretion group had a significantly higher prevalence of hyperuricaemia than the high urinary glucose excretion group. Moreover, urinary glucose excretion was negatively associated with uric acid level. The correlation remained significant after adjusting for potential confounders, including gender, age, fasting plasma glucose, 2-h plasma glucose and BMI. The results also showed that participants with high urinary glucose excretion were at decreased risk of hyperuricaemia (odds ratio 0.47, 95% CI 0.27-0.80; P = 0.006).

CONCLUSION

Urinary glucose excretion was independently associated with uric acid level in participants with newly diagnosed diabetes. In addition to lowering blood glucose, promoting urinary glucose excretion may also be an effective approach to reducing serum uric acid levels, especially for people with diabetes complicated with hyperuricaemia.

Metabolites related to purine catabolism and risk of type 2 diabetes incidence; modifying effects of the TCF7L2-rs7903146 polymorphism

Studies examining associations between purine metabolites and type 2 diabetes (T2D) are limited. We prospectively examined associations between plasma levels of purine metabolites with T2D risk and the modifying effects of transcription factor-7-like-2 (TCF7L2) rs7903146 polymorphism on these associations. This is a case-cohort design study within the PREDIMED study, with 251 incident T2D cases and a random sample of 694 participants (641 non-cases and 53 overlapping cases) without T2D at baseline (median follow-up: 3.8 years). Metabolites were semi-quantitatively profiled with LC-MS/MS. Cox regression analysis revealed that high plasma allantoin levels, including allantoin-to-uric acid ratio and high xanthine-to-hypoxanthine ratio were inversely and positively associated with T2D risk, respectively, independently of classical risk factors. Elevated plasma xanthine and inosine levels were associated with a higher T2D risk in homozygous carriers of the TCF7L2-rs7903146 T-allele. The potential mechanisms linking the aforementioned purine metabolites and T2D risk must be also further investigated.

SGLT2 inhibition and renal urate excretion: role of luminal glucose, GLUT9, and URAT1

Inhibitors of the Na⁺-glucose cotransporter SGLT2 enhance urinary glucose and urate excretion and lower plasma urate levels. The mechanisms remain unclear, but a role for enhanced glucose in the tubular fluid, which may interact with tubular urate transporters, such as the glucose transporter GLUT9 or the urate transporter URAT1, has been proposed. Studies were performed in nondiabetic mice treated with the SGLT2 inhibitor canagliflozin and in gene-targeted mice lacking the urate transporter Glut9 in the tubule or in mice with whole body knockout of Sglt2, Sglt1, or Urat1. Renal urate handling was assessed by analysis of urate in spontaneous plasma and urine samples and normalization to creatinine concentrations or by renal clearance studies with assessment of glomerular filtration rate by FITC-sinistrin. The experiments confirmed the contribution of URAT1 and GLUT9 to renal urate reabsorption, showing a greater contribution of the latter and additive effects. Genetic and pharmacological inhibition of SGLT2 enhanced fractional renal urate excretion (FE-urate), indicating that a direct effect of the SGLT2 inhibitor on urate transporters is not absolutely necessary. Consistent with a proposed role of increased luminal glucose delivery, the absence of Sglt1, which by itself had no effect on FE-urate, enhanced the glycosuric and uricosuric effects of the SGLT2 inhibitor. The SGLT2 inhibitor enhanced renal mRNA expression of Glut9 in wild-type mice, but tubular GLUT9 seemed dispensable for the increase in FE-urate in response to canagliflozin. First evidence is presented that URAT1 is required for the acute uricosuric effect of the SGLT2 inhibitor in mice.

Cardiovascular Disease and Gout: Real-World Experience Evaluating Patient Characteristics, Treatment Patterns, and Health Care Utilization

BACKGROUND

Gout, hyperuricemia, and cardiovascular disease (CVD) are prevalent conditions in the United States, and while they share common risk factors such as obesity, hypertension, hypercholesterolemia, and type 2 diabetes mellitus, relatively little is known about what patient and disease characteristics may link CVD with hyperuricemia and gout and how the presence of both diseases affects management decisions differently than for patients with gout alone.

OBJECTIVE

To identify differences in patient characteristics, patterns of urate-lowering therapy (ULT) use, and gout control in gout patients with and without cardiovascular comorbidity.

METHODS

Data were assessed from a survey of U.S. physicians who performed in-depth patient chart audits of their last 5 consecutive adult patients with confirmed gout as determined by the medical record and clinical notes. Comorbidities, gout symptoms, length of current treatment, sociodemographic factors, and physician type were identified from the chart review. Descriptive statistics and logistic regression described differences among patients with and without comorbid CVD and assessed ULT use and gout control.

RESULTS

Of the 1,159 patient charts that were reviewed, 738 patients had CVD and gout, and 421 had gout alone. Patients with CVD had longer duration of gout (mean [SD] = 52 [68.2] vs. 34 [47.2] months; P < 0.001) and were more likely to have clinician-reported tophi (28% vs. 15%; P < 0.001), organ/joint damage (19% vs. 9%; P < 0.001), and more flares (2.1% vs. 1.8%; P = 0.017) in the previous 12 months. Time from gout diagnosis to start of ULT was delayed for those with CVD (mean [SD] = 24.3 [56.6] vs. 15.5 [33.2] months; P = 0.023), but these patients were more likely to be receiving ULT (83% vs. 59%; P < 0.001). Gout patients with CVD were more likely to have a variety of additional comorbidities than those without CVD, such as obesity (28% vs. 18%; P < 0.001), diabetes (26% vs. 12%; P < 0.001), osteoarthritis (25% vs. 11%; P < 0.001), chronic kidney disease (17% vs. 5%; P < 0.001), and prostate disease (males, n = 933; 10% vs. 2%; P < 0.001). Gout patients with CVD were more likely to have an emergency department visit (12% vs. 7%; P = 0.003) for gout in the previous 12 months. In patients with CVD, ULT use was associated with better gout control.

CONCLUSIONS

Gout patients with CVD were more likely to have additional comorbidities, more gout-related symptoms, and a delay in initiating treatment, which may be associated with the greater severity of disease in these patients. These data suggest that gout patients with CVD may constitute a less healthy group in need of earlier, more aggressive therapy.

DISCLOSURES

This study was supported by AstraZeneca. Pillinger reports consultancies at AstraZeneca, SOBI, Crealta/Horizon; investigator-initiated grants from Takeda (closed 2016); and was an investigator on industry-sponsored clinical trials for Takeda. Klein is employed by AstraZeneca. At the time of this study, Baumgartner was employed by Ardea Biosciences, a wholly owned subsidiary of AstraZeneca and owns stock in AstraZeneca. Baumgartner and Morlock are consultants to Ardea Biosciences. Morlock reports consulting fees from Genentech, Ironwood Pharmaceuticals, Astellas, and Abbot Medical Optics outside of this study. Bangalore reports consultancies at Pfizer, Merck, Abbott Vascular, Medicines Company, AstraZeneca, and the National Heart, Lung, and Blood Institute. The authors did not receive any honoraria for this publication. Study concept and design were primarily contributed by Morlock, along with the other authors. Morlock collected the data, and data interpretation was performed by all the authors. All authors equally contributed to preparation and revision of the manuscript. Preliminary results from this study were presented at the AMCP Managed Care & Specialty Pharmacy Annual Meeting 2016; San Francisco, California; April 19-22, 2016.

Hyperuricemia and overexcretion of uric acid increase the risk of simple renal cysts in type 2 diabetes

Previous studies have discussed the relationship between simple renal cysts (SRC) and serum uric acid level in healthy individuals. We performed a cross-sectional study to evaluate the association between serum uric acid level and fractional excretion of uric acid (FEUA) and simple renal cysts in males and postmenopausal females with type 2 diabetes. The overall prevalence of SRC was 18.1% in our population. SRC prevalence was significantly higher in hyperuricemic than normouricemic subjects (27.3% vs. 16.8%, P < 0.001). Subjects who overexcreted uric acid had a higher prevalence of SRC than underexcretors (total population: 21.6% vs. 16.3%; normouricemic subjects: 19.8% vs. 13.7%; hyperuricemic subjects: 50.0% vs. 22.7%, all P-values < 0.05). Hyperuricemia (odds ratio [OR] 1.824, 95% confidence interval [CI] 1.332-2.498, P < 0.001); FEUA (OR 1.046, 95% CI 1.002-1.091, P < 0.05); male gender (OR 1.922, 95% CI 1.489-2.480, P < 0.001); age (OR 1.049, 95% CI 1.035-1.064, P < 0.001); and albuminuria (OR 1.492, 95% CI 1.176-1.892, P < 0.01) were independent risk factors for SRC development. These findings suggested that hyperuricemia and high level of FEUA were both independent risk factors for SRC development in males and postmenopausal females with type 2 diabetes. Half of overproduction hyperuricemic patients had SRC.

High serum uric acid levels increase the risk of metabolic syndrome in elderly women: The PRO.V.A study

BACKGROUND AND AIMS

Serum uric acid (SUA) is the end-product of purine metabolism in humans, and its levels often increase in subjects with metabolic syndrome (MetS). Despite several studies demonstrating a relationship between increased SUA levels and the prevalence of MetS, prospective data on SUA as a predictor of the incidence of MetS in the elderly are limited. Our aim was to conduct a prospective study on the association between SUA concentrations and the onset of MetS in an elderly Italian cohort.

METHODS AND RESULTS

This is a cohort study (Progetto Veneto Anziani; Pro.V.A.) involving community-dwelling subjects aged ≥65 years and followed up for a mean 4.4 years. We included 1128 participants (aged 74.7 ± 7.1 years) without MetS at the baseline. Gender-specific SUA groups according to the standard deviation (SD) from the mean were considered, taking the incidence of MetS as the main outcome. The mean SUA level was significantly higher in men than in women (5.4 ± 1.2 vs. 4.5 ± 1.2 mg/dl; p < 0.0001). Over the 4.4-year follow-up, 496 individuals developed MetS. After adjusting for potential confounders, Cox's regression analysis revealed no relationship between higher baseline SUA concentrations and the incidence of MetS in men or in the sample as whole, while women with SUA levels more than 1 SD above the mean (≥5.7 mg/dl) carried a 58% higher risk (95%CI: 1.03-2.40; p = 0.03) of being newly diagnosed with MetS during the follow-up.

CONCLUSION

High SUA levels significantly and independently predicted MetS in older women, but not in men, over a 4.4-year follow-up.

Progressive Changes in the Plasma Metabolome during Malnutrition in Juvenile Pigs

Severe acute malnutrition (SAM) is one of the leading nutrition-related causes of death in children under five years of age. The clinical features of SAM are well documented, but a comprehensive understanding of the development from a normal physiological state to SAM is lacking. Characterizing the temporal metabolomic change may help to understand the disease progression and to define nutritional rehabilitation strategies. Using a piglet model we hypothesized that a progressing degree of malnutrition induces marked plasma metabolite changes. Four-week-old weaned pigs were fed a nutrient-deficient maize diet (MAL) or nutritionally optimized reference diet (REF) for 7 weeks. Plasma collected weekly was subjected to LC-MS for a nontargeted profiling of metabolites with abundance differentiation. The MAL pigs showed markedly reduced body-weight gain and lean-mass proportion relative to the REF pigs. Levels of eight essential and four nonessential amino acids showed a time-dependent deviation in the MAL pigs from that in the REF. Choline metabolites and gut microbiomic metabolites generally showed higher abundance in the MAL pigs. The results demonstrated that young malnourished pigs had a profoundly perturbed metabolism, and this provides basic knowledge about metabolic changes during malnourishment, which may be of help in designing targeted therapeutic foods for refeeding malnourished children.

Probing SGLT2 as a therapeutic target for diabetes: basic physiology and consequences

Traditional treatments for type 1 and type 2 diabetes are often associated with side effects, including weight gain and hypoglycaemia that may offset the benefits of blood glucose lowering. The kidneys filter and reabsorb large amounts of glucose, and urine is almost free of glucose in normoglycaemia. The sodium-dependent glucose transporter (SGLT)-2 in the early proximal tubule reabsorbs the majority of filtered glucose. Remaining glucose is reabsorbed by SGLT1 in the late proximal tubule. Diabetes enhances renal glucose reabsorption by increasing the tubular glucose load and the expression of SGLT2 (as shown in mice), which maintains hyperglycaemia. Inhibitors of SGLT2 enhance urinary glucose excretion and thereby lower blood glucose levels in type 1 and type 2 diabetes. The load-dependent increase in SGLT1-mediated glucose reabsorption explains why SGLT2 inhibitors in normoglycaemic conditions enhance urinary glucose excretion to only ~50% of the filtered glucose. The role of SGLT1 in both renal and intestinal glucose reabsorption provides a rationale for the development of dual SGLT1/2 inhibitors. SGLT2 inhibitors lower blood glucose levels independent of insulin and induce pleiotropic actions that may be relevant in the context of lowering cardiovascular risk. Ongoing long-term clinical studies will determine whether SGLT2 inhibitors have a safety profile and exert cardiovascular benefits that are superior to traditional agents.