The utility of urinary myo-inositol as a marker of glucose intolerance

Characteristics of individuals who developed type 2 diabetes from prediabetes despite undergoing interventions, and evaluation of the performance of urinary myo-inositol as a risk factor for developing diabetes

AIMS/INTRODUCTION

The aim of this study was to clarify the characteristics of individuals with prediabetes who developed type 2 diabetes despite undergoing interventions, and to evaluate the performance of urinary myo-inositol (UMI) as a noninvasive indicator for the risk of developing diabetes.

MATERIALS AND METHODS

A total of 51 individuals with prediabetes who underwent a 75-g oral glucose tolerance test, ΔUMI (the difference in the UMI : creatinine ratio between before and 120 min after 75-g glucose loading), fasting plasma glucose, insulin, hemoglobin A1c, noninvasive testing (age, body mass index, blood pressure) and general blood tests were measured at baseline, and underwent dietary/exercise guidance for 8 years were studied.

RESULTS

A total of 31 participants developed diabetes in 8 years. At baseline, the group that developed diabetes was characterized by high ΔUMI, hemoglobin A1c, fasting plasma glucose and low high-density lipoprotein cholesterol, and insulinogenic index (I.I.). I.I and ΔUMI showed a higher correlation than fasting plasma glucose and hemoglobin A1c. Regarding diabetes onset within 8 years, Cox regression analysis of diabetes onset showed the baseline ΔUMI is an independent predictor, adjusted for the result of not only noninvasive markers, but also that of noninvasive and general blood markers. The log-rank test showed that all glycemic indicators were significantly associated with diabetes onset.

CONCLUSION

Participants who developed type 2 diabetes from prediabetes despite undergoing interventions were characterized by high glycemic control markers and low I.I. As noninvasive measurement of ΔUMI is associated with I.I. and diabetes onset, it could be a useful indicator for identifying individuals with a high risk of diabetes onset.

Myo-inositol oxygenese activity in second trimester of pregnancy: altered myoinositol catabolism in gestational diabetes mellitus

OBJECTIVE

We aimed to determine myo-inositol oxygenase (MIOX) activity in gestational diabetes mellitus (GDM).

MATERIAL AND METHODS

The insulin, HbA1c, and MIOX levels of 80 pregnant women were analysed after 75 g OGTT. Group I included patients with no risk factor for GDM, Group II: patients with high risk for GDM, and Group III: GDM patients.

RESULTS

Fasting plasma glucose and Homeostatic Model Assessment for Insulin Resistance index were significantly higher in GDM cases (Group 3). Regarding the MIOX levels, significantly higher levels were recorded at 0-h in Group 3 compared to Groups 1 and 2. Significant alteration in MIOX activity was found between 0- and 2-h in Group 3 compared to Groups 1 and 2 (p < .029).

CONCLUSIONS

MIOX levels were higher in GDM cases so, it may be have a role in myo-inositol catabolism.

Kyushu and Okinawa Population Study (KOPS): a large prospective cohort study in Japan

PURPOSE

The Kyushu and Okinawa Population Study (KOPS) was established to investigate gene-environmental interactions in non-communicable diseases in Japan. Besides collecting blood samples and anthropometric measurements, we also obtained medical histories, psychological status and lifestyle habits, including physical activities and dietary patterns.

PARTICIPANTS

KOPS is a community-based prospective cohort study and consists of participants from four southwestern areas in Japan. Baseline surveys were conducted between 2004 and 2007 (wave 1), and 2009 and 2012 (wave 2) at the sites of municipality-based health check-ups. A total of 17 077 participants were included, comprising 10 697 participants of wave 1 and 6380 participants of wave 2; the median age in both groups was 61 years. Among them, 3006 individuals participated in both wave 1 and wave 2 surveys.

FINDINGS TO DATE

We have focused on either risk or confounding factors for non-communicable diseases. We have assessed the clinical utility of the newly developed biomarkers for impaired glucose tolerance, such as urinary myo-inositol and glycated albumin, and atherosclerosis, such as small dense low-density lipoprotein cholesterol. We have conducted an international collaborative study with Framingham Offspring Study to investigate ethnic differences in impaired glucose tolerance and cardiovascular diseases. We have found that insulin resistance and deficiency might account for the ethnic differences in impaired glucose tolerance and cardiovascular disease risks. As gene-environmental interaction analyses, we found a synergic effect of interleukin 28B single nucleotide polymorphisms (SNPs) and gender on the spontaneous elimination of hepatitis C, and a beneficial interaction of SNPs of high-density lipoprotein cholesterol and gender on the impact of physical activity. In addition, we reported eight novel loci contributing to the development and severity of coronary artery disease from a large genome-wide association study.

FUTURE PLANS

We plan to investigate further the clinical utility of the newly developed biomarkers and the gene-environmental interactions using prospective data.

A Multi-Platform Metabolomics Approach Identifies Urinary Metabolite Signatures That Differentiate Ketotic From Healthy Dairy Cows

Ketosis and subclinical ketosis are widespread among dairy cows especially after calving. Etiopathology of ketosis has been related to negative energy balance. The objective of this study was to investigate metabolite fingerprints in the urine of pre-ketotic, ketotic, and post-ketotic cows to identify potential metabolite alterations that can be used in the future to identify susceptible cows for ketosis and metabolic pathways involved in the development of disease. In this study, NMR, DI/LC-MS/MS, and GC-MS-based metabolomics were used to analyze urine samples from 6 cows diagnosed with ketosis and 20 healthy control (CON) cows at -8 and -4 weeks prepartum, the week (+1 to +3) of ketosis diagnosis, and at +4 and +8 weeks after parturition. Univariate and multivariate analyses were used to screen metabolite panels that can identify cows at their pre-ketotic stage. A total of 54, 42, 48, 16, and 31 differential metabolites between the ketotic and CON cows were identified at -8 and -4 weeks prepartum, ketosis week, and at +4, and +8 weeks postpartum, respectively. Variable importance in projection (VIP) plots ranked the most significant differential metabolites, which differentiated ketotic cows from the CON ones. Additionally, several metabolic pathways that are related to ketosis were identified. Moreover, two promising metabolite panels were identified which clearly separated ketotic from CON cows with excellent level of sensitivity and specificity. Overall, multiple urinary metabolite alterations were identified in pre-ketotic, ketotic, and post-ketotic cows. The metabolite panels identified need to be validated in the future in a larger cohort of animals.

Plasma and urinary inositol isomer profiles measured by UHPLC-MS/MS reveal differences in scyllo-inositol levels between non-pregnant and pregnant women

Previous studies support that myo- and D-chiro-inositol isomers are promising bioactives for the treatment of women with polycystic ovary syndrome and for lowering the risk of gestational diabetes mellitus in pregnant women, whereas scyllo-inositol may have some benefits for neurological disorders (e.g., Alzheimer's disease). Though potentially useful to better understand inositol isomer metabolism and study their role in health and disease, routine analysis of inositol isomers in plasma and urine with a single analytical method is not yet feasible due to the lack of a suitable analytical assay. To address this, we developed and validated a robust ultra-high-performance-liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method for the quantification of inositol isomers in plasma and urine. This method resolves seven inositol isomers with accurate quantification of total chiro- (D and L enantiomers), myo-, and scyllo-inositols and is semi-quantitative for neo-inositol. For urine and plasma myo-inositol, the method repeatability and intermediate reproducibility were below 6% and 8%, respectively. Then, for both chiro- and scyllo-inositols, repeatability and intermediate reproducibility were below 10% and 14%, respectively. A pilot study was carried out to quantify and compare the pattern of inositol isomers in urine and plasma of non-pregnant and pregnant women and showed for the first time that urinary myo- and scyllo-inositol concentrations were significantly higher for women in the third trimester of pregnancy compared with non-pregnant women. These findings warrant further research to understand the biological significance of the observed differences in inositol profiles and suggest a potential role of scyllo-inositol.Graphical abstract Plasma and urinary inositol isomer profiles measured by UHPLC-MS/MS reveal differences in scyllo-inositol levels between non-pregnant and pregnant women.

Amperometric determination of Myo-inositol using a glassy carbon electrode modified with nanostructured copper sulfide

A method for the amperometric determination of Myo-inositol is presented. Nanostructured copper sulfide material was synthesized by solvothermal method and utilized as sensor matrix. The physico-chemical analysis using XRD, Raman, FE-SEM, TEM, and XPS confirmed the formation of CuS material. The voltammetric response of CuS-modified glassy carbon electrode for a successive Myo-inositol (0.5 μM) addition confirmed that the reaction takes place at the surface of the electrode. The modified electrode resulted in signal enhancement for a linear response ranging from 0.5-8.5 μM at an applied overpotential of 0.65 V with a correlation coefficient value (R²) of 0.99. The sensitivity and limit of detection of the modified electrode were 7.87 μA μM^-1 cm^-2 and 0.24 μM, respectively. The interfering effect of various compounds present in real samples was examined. Graphical abstract Schematic representation of synthetic protocol of nanostructured CuS and Myo-inositol oxidation on CuS-modified glassy carbon electrode in basic medium.

Simple and non-invasive screening method for diabetes based on myoinositol levels in urine samples collected at home

OBJECTIVE

To establish a simple screening method for diabetes based on myoinositol (MI) in urine samples collected at home.

RESEARCH DESIGN AND METHODS

Initially, we evaluated the stability of urinary MI (UMI) at room temperature (RT; 25°C) and 37°C in 10 outpatients with type 2 diabetes. We then enrolled 115 volunteers without a current or history of diabetes. In all subjects, glucose intolerance was diagnosed by 75 g oral glucose tolerance test (75gOGTT). To assess the association between UMI or urine glucose (UG) and plasma glucose (PG), urine samples were also collected at 0 and 2 hours during 75gOGTT. All the subjects collected urine samples at home before and 2 hours after consuming the commercially available test meal. UMI levels at wake-up time (UMI_wake-up), before (UMI_premeal) and 2 hours after the test meal (UMI_{2h-postprandial}) were measured using an enzymatic method. ΔUMI was defined as UMI_{2h-postprandial} minus UMI_premeal.

RESULTS

Differing from UG, UMI was stable at RT and 37°C. UMI was increased linearly along with an increase in PG, and no threshold for UMI was observed. UMI was closely associated with blood glucose parameters obtained from a 75gOGTT and hemoglobin A1c (HbA1c) at hospital after adjustment for age, sex, body mass index and serum creatinine. UMI_wake-up, UMI_premeal, UMI_{2h-postprandial} and ΔUMI at home were higher in diabetic subjects than non-diabetic subjects even after the above adjustment. Receiver operating characteristics curve (ROC) analyses revealed that for the screening of diabetes, the area under the curve for ROC for UMI_{2h-postprandial} and ΔUMI (0.83 and 0.82, respectively) were not inferior to that for HbA1c ≥48 mmol/mol, which is the American Diabetes Association (ADA) criteria for diabetes.

CONCLUSIONS

MI measurement in urine samples collected at home before and after the meal would be a simple, non-invasive and valuable screening method for diabetes.

Serum Ethanolamine Plasmalogen and Urine Myo-Inositol as Cognitive Decline Markers

Recent studies have suggested that metabolic disorders, particularly type 2 diabetes mellitus (T2DM), and dementia, including Alzheimer's disease (AD), were linked at the clinical and molecular levels. Brain insulin deficiency and resistance may be key events in AD pathology mechanistically linking AD to T2DM. Ethanolamine plasmalogens (PlsEtns) are abundant in the brain and play essential roles in neuronal function and myelin formation. As such, PlsEtn deficiency may be pathologically relevant in some neurodegenerative disorders such as AD. Decreased brain PlsEtn associated with dementia may reflect serum PlsEtn deficiency. We hypothesized that myo-inositol plays a role in myelin formation through its facilitation of PlsEtn biosynthesis. Excessive urinary myo-inositol (UMI) loss would likely result in PlsEtn deficiency potentially leading to demyelinating diseases such as dementia. Accordingly, measurement of both serum PlsEtn and baseline UMI excretion could improve the detection of cognitive impairment (CI) in a more specific and reliable manner. To verify our hypothesis, we conducted a clinical observational study of memory clinic outpatients (MCO) and cognitively normal elderly (NE) for nearly 4.5years. We demonstrated that serum PlsEtn concentration associated with UMI excretion was useful for predicting advancing dementia in patients with mild CI. Because hyperglycemia and associated insulin resistance might be a leading cause of increased baseline UMI excretion, serum PlsEtn quantitation would be useful in detecting CI among the elderly with hyperglycemia. Our findings suggest that myo-inositol is a novel candidate molecule linking T2DM to AD.

Metabolic phenotyping of malnutrition during the first 1000 days of life

Nutritional restrictions during the first 1000 days of life can impair or delay the physical and cognitive development of the individual and have long-term consequences for their health. Metabolic phenotyping (metabolomics/metabonomics) simultaneously measures a diverse range of low molecular weight metabolites in a sample providing a comprehensive assessment of the individual's biochemical status. There are a growing number of studies applying such approaches to characterize the metabolic derangements induced by various forms of early-life malnutrition. This includes acute and chronic undernutrition and specific micronutrient deficiencies. Collectively, these studies highlight the diverse and dynamic metabolic disruptions resulting from various forms of nutritional deficiencies. Perturbations were observed in many pathways including those involved in energy, amino acid, and bile acid metabolism, the metabolic interactions between the gut microbiota and the host, and changes in metabolites associated with gut health. The information gleaned from such studies provides novel insights into the mechanisms linking malnutrition with developmental impairments and assists in the elucidation of candidate biomarkers to identify individuals at risk of developmental shortfalls. As the metabolic profile represents a snapshot of the biochemical status of an individual at a given time, there is great potential to use this information to tailor interventional strategies specifically to the metabolic needs of the individual.

The Relation between Serum Endostatin Level and Carotid Atherosclerosis in Healthy Residents of Japan: Results from the Kyushu and Okinawa Population Study (KOPS)

AIM

To examine the association between the serum endostatin levels and subclinical atherosclerosis independent of traditional risk factors in a healthy Japanese population.

METHODS

Among 1,057 residents who attended free public physical examinations between 2010 and 2011, we evaluated the data of 648 healthy residents for whom the serum endostatin level and common carotid intima-media thickness (IMT) were successfully measured.

RESULTS

The median endostatin level was 63.7 ng/mL (interquartile ranges: 49.7-93.2 ng/mL), and the mean carotid IMT was 0.68±0.12 mm. Residents with above median endostatin had significantly higher carotid IMT than did those with below median endostatin (0.71±0.14 vs. 0.65±0.09 mm, P＜0.001). Multiple linear regression analysis demonstrated that increased serum endostatin is significantly associated with carotid IMT (above vs. below median endostatin level; beta=0.11, P=0.03), independent of the known covariates of age, sex, body mass index, drinking and smoking status, systolic blood pressure, diastolic blood pressure, hemoglobin A1c, low density lipoprotein cholesterol, estimated glomerular filtration rate, and log-transformed high sensitive C-reactive protein.

CONCLUSIONS

A higher serum endostatin level reflected subclinical atherosclerosis in this Japanese population.

The relation of postprandial plasma glucose and serum endostatin to the urinary albumin excretion of residents with prediabetes: results from the Kyushu and Okinawa Population Study (KOPS)

BACKGROUND

Previous clinical studies have shown that the circulating level of endostatin is related to kidney injury. We hypothesized that the impact of HbA1c, fasting, and postprandial plasma glucose on urinary albumin excretion would be related to the serum endostatin level.

METHODS

A cross-sectional, community-based population study of 1057 Japanese residents was conducted. Of these subjects, 162 with a fasting plasma glucose value between 5.5 and 6.9 mmol/L and an HbA1c level of <6.5 % received an oral glucose tolerance test, had serum endostatin measured, and had the urinary albumin/creatinine ratio (UACR) calculated.

RESULTS

In multivariate analysis, 2-h postprandial plasma glucose (β = 0.26, P < 0.01) was significantly associated with log-transformed UACR, independently of fasting plasma glucose (β = 0.14, P = 0.28) and HbA1c (β = -0.08, P = 0.57). When divided by the median value of endostatin (82.2 ng/mL), 2-h postprandial plasma glucose (β = 0.38, P = 0.01) remained significantly associated with the log-transformed UACR of the participants below the median, while the fasting plasma glucose (β = 0.34, P = 0.046) was independently associated with the log-transformed UACR of participants above the median.

CONCLUSION

Postprandial plasma glucose was independently associated with the urinary albumin excretion of the residents with prediabetes. Moreover, this relationship was limited to residents with a serum endostatin level below the median.

Urinary myo-inositol levels in Japanese schoolchildren with normal glucose tolerance

BACKGROUND

Urinary myo-inositol (UMI) level is elevated in adult diabetic patients, and also increases after glucose loading. However, the relationship between UMI and plasma glucose levels in children is unknown. We aimed to assess whether UMI is a practical marker for glucose intolerance in children or not.

METHODS

In Study 1 (328 schoolchildren), fasting and postprandial UMI were measured, with ΔUMI defined as the difference between fasting and postprandial UMI levels. In Study 2, oral glucose tolerance tests and UMI measurements were conducted in 18 children with suspected having diabetes.

RESULTS

For Study 1, ΔUMI was observed [-0.65 (-3.9, 1.35) mg/g creatinine]. For Study 2, children with diabetes or impaired glucose tolerance had a significantly higher ΔUMI than children with normal glucose tolerance.

CONCLUSIONS

These studies demonstrated the normal range of UMI in children and possibility of a novel biomarker for early detection of glucose intolerance in children.

Serum ethanolamine plasmalogens improve detection of cognitive impairment among elderly with high excretion levels of urinary myo-inositol: A cross-sectional study

BACKGROUND

Several reports have implicated myo-inositol (MI) in myelin formation. We hypothesized that MI is involved in this process through facilitating the biosynthesis of ethanolamine plasmalogens (PlsEtns), which are the major component of myelin membranes, and essential for myelin formation and function. Excessive MI urinary excretion possibly causes PlsEtn deficiency, leading to demyelinating diseases including dementia.

METHODS

We examined the association between cognitive impairment, serum levels of PlsEtn, and baseline levels of urinary MI excretion, in the enrollment of 55 memory clinic outpatients and 107 cognitively normal elderly.

RESULTS

Serum PlsEtns were independently associated with cognitive impairment, and significantly reduced in memory clinic outpatients, especially in those with high urinary MI, as compared to normal elderly. On the other hand, there was no direct association between urinary MI and cognitive impairment, but urinary MI was significantly associated with serum hemoglobin A1c and amyloid β 1-40. The interaction between PlsEtn and urinary MI for cognitive impairment was statistically confirmed, and their combined usage improved diagnosis of cognitive impairment.

CONCLUSIONS

We proposed the involvement of MI and PlsEtn in cognitive impairment pathology. In conclusion, serum PlsEtn may be useful in detecting cognitive decline among elderly with hyperglycemia.

Subclinical carotid atherosclerosis and triglycerides predict the incidence of chronic kidney disease in the Japanese general population: results from the Kyushu and Okinawa Population Study (KOPS)

OBJECTIVE

To examine whether or not subclinical atherosclerosis independently predicts the incidence of chronic kidney disease (CKD) in the Japanese general population.

METHODS

This study is part of the Kyushu and Okinawa Population Study (KOPS), a survey of vascular events associated with lifestyle-related diseases. Participants who attended both baseline (2004-2007) and follow-up (2009-2012) examinations were eligible. The common carotid intima-media thickness (IMT) was assessed for each participant at baseline. The end point was the incidence of CKD, defined as an estimated glomerular filtration rate (eGFR) < 60 mL/min/1.73 m(2) during the follow-up of participants without CKD at baseline.

RESULTS

During the five-year follow-up, 224 of the 1824 participants (12.3%) who developed CKD had higher carotid IMT (0.74 ± 0.22 vs. 0.65 ± 0.14 mm, P < 0.001), higher triglycerides (1.6 ± 0.8 vs. 1.3 ± 0.7 mmol/L, P < 0.001), and lower high density lipoprotein cholesterol (1.5 ± 0.4 vs. 1.6 ± 0.4 mmol/L, P < 0.001) at baseline than those who did not. In logistic regression analysis adjusted for significant covariates, eGFR (Odds ratio [OR] 0.83, 95% confidence interval (CI) 0.80-0.85, P < 0.001), carotid IMT (0.10 mm increase: OR 1.17, 95% CI 1.04-1.33, P = 0.010), and triglycerides (OR 1.35, 95% CI 1.06-1.73, P = 0.015) at baseline were independent predictors for the development of CKD.

CONCLUSIONS

Higher carotid IMT and hypertriglyceridemia were independently associated with the development of CKD in the population studied.