A study of urinary myo-inositol as a sensitive 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.

Serum metabolites associated with increased insulin resistance and low cardiorespiratory fitness in overweight adolescents

BACKGROUND AND AIMS

Obesity affects metabolism, increasing the risk of developing non-communicable diseases in adolescence, due to excess adipose tissue and low cardiorespiratory fitness (CRF). The metabolomics approach allows the elucidation of metabolites, which may have the concentrations altered by several factors, such as body composition (BC). We aimed to analyze the metabolomic profile of normal-weight and overweight adolescents and associate the metabolites with clinical markers related to BC, insulin resistance (IR), and CRF.

METHODS AND RESULTS

The sample was composed of 57 adolescents and divided into two groups: the normal-weight group (NWG, n = 24) and the overweight group (OWG, n = 33). They underwent blood collection and anthropometric, BC, and CRF assessment. Blood serum samples were analyzed by ¹H-NMR spectroscopy (600 MHz). The OWG presented higher values of body weight (BW), body mass index (BMI), waist circumference (WC), fasting glucose, insulin, IR, cholesterol, and percentage of fat mass (%FM) and lower levels of peak oxygen consumption (VO₂ peak) compared with the NWG. The OWG presented lower concentrations of 3-hydroxyisovalerate, glutamate, and methionine as well as higher concentrations of aspartate, asparagine, creatine, glycerol, myo-inositol, proline, pyruvate, tyrosine, and valerate compared with the NWG. The concentrations of glutamate, myo-inositol, creatine, methionine, and valerate correlated with %FM; pyruvate and valerate positively correlated with IR; and glutamate, tyrosine, and valerate negatively correlated with CRF.

CONCLUSION

Changes in the BC lead to changes in the metabolomic profile of adolescents, and the altered metabolites are associated with increased IR and low CRF. These results indicate new targets for health monitoring and prevention of cardiovascular and metabolic diseases in adolescents.

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.

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.

Myo-inositol: its metabolism and potential implications for poultry nutrition-a review

Myo-inositol (MI) has gained relevance in physiology research during the last decade. As a constituent of animal cells, MI was proven to be crucial in several metabolic and regulatory processes. Myo-inositol is involved in lipid signaling, osmolarity, glucose, and insulin metabolism. In humans and rodents, dietary MI was assessed to be important for health so that MI supplementation appeared to be a valuable alternative for treatment of several diseases as well as for improvements in metabolic performance. In poultry, there is a lack of evidence not only related to specific species-linked metabolic processes but also about the effects of dietary MI on performance and health. This review intends to provide information about the meaning of dietary MI in animal metabolism as well as to discuss potential implications of dietary MI in poultry health and performance with the aim to identify open questions in poultry research.

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.

Phytases Improve Myo-Inositol Bioaccessibility in Rye Bread: A Study Using an In Vitro Method of Digestion and a Caco-2 Cell Culture Model

Preparations of 6-phytase A (EC 3.1.3.26) and phytase B (acid phosphatase, EC 3.1.3.2) were applied alone and combined in the preparation of dough to estimate their catalytic potential for myo-inositol liberation from rye flour in the breadmaking technology. The experimental bread samples were ground after baking and subjected to determination of myo-inositol bioavailability by an in vitro method that simulated digestion in a human alimentary tract, followed by measurements of myo-inositol transport through enterocyte- -like differentiated Caco-2 cells to determine its bioaccessibility. Myo-inositol content was measured by a high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) technique. The concentration of myo-inositol in the dialysates of control bread was 25.3 µg/mL, whereas in the dialysates of bread sample baked with 6-phytase A, the concentration increased to 35.4 µg/mL, and in the bread baked with phytase B to 64.98 µg/mL. Simultaneous application of both enzymes resulted in myo-inositol release of 64.04 µg/mL. The highest bioaccessibility of myo-inositol, assessed by the measurement of the passage through the Caco-2 monolayer was determined in the bread baked with the addition of 6-phytase A. Enzymatically modified rye bread, particularly by the addition of 6-phytase A, may be therefore a rich source of a highly bioaccessible myo- -inositol.

Exploratory analysis of urinary tract infection using a GC-APCI-MS platform

This study shows the first application of GC-APCI-MS in a clinical setting specifically in the context of urinary tract infection.

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

OBJECTIVE

The most common screening tests for glucose intolerance are fasting plasma glucose (FPG) and glycated hemoglobin (HbA1c). Because it reflects the current status of hyperglycemia, urinary myo-inositol (UMI) may be useful. We evaluated UMI as a screening tool for glucose intolerance.

DESIGN AND METHODS

A cross-sectional, community-based population study of 1057 Japanese residents. 173 with an FPG level between 5.5 and 6.9 mmol/L and an HbA1c under 6.5% had an oral glucose tolerance test. We measured UMI level before (fasting UMI) and 2h after (2h-UMI) glucose ingestion. Δ-UMI was defined as the difference between fasting UMI and 2h-UMI.

RESULTS

Δ-UMI, 2h-UMI and HbA1c levels significantly increased as glucose intolerance worsened. Δ-UMI level was significantly positively correlated with 2h-UMI level (r=0.896, p<0.001). Using cutoff levels from receiver operating characteristic (ROC) analyses, the sensitivity of Δ-UMI (82.1%) and 2h-UMI (79.3%) were higher than that of HbA1c (48.3%). The area under the ROC curve values for Δ-UMI (0.903) and 2h-UMI (0.891) were higher than that for HbA1c (0.785).

CONCLUSIONS

2h-UMI is useful as a non-invasive screening of glucose intolerance.

Metabolomics reveals relationship between plasma inositols and birth weight: possible markers for fetal programming of type 2 diabetes

Epidemiological studies in man and with experimental animal models have shown that intrauterine growth restriction (IUGR) resulting in low birth weight is associated with higher risk of programming welfare diseases in later life. In the pig, severe IUGR occurs naturally and contribute substantially to a large intralitter variation in birth weight and may therefore be a good model for man. In the present paper the natural form of IUGR in pigs was studied close to term by nuclear magnetic resonance (NMR-)based metabolomics. The NMR-based investigations revealed different metabolic profiles of plasma samples from low-birth weight (LW) and high-birth weight (HW) piglets, respectively, and differences were assigned to levels of glucose and myo-inositol. Further studies by GC-MS revealed that LW piglets had a significant higher concentration of myoinositol and D-chiro-inositol in plasma compared to larger littermates. Myo-inositol and D-chiro-inositol have been coupled with glucose intolerance and insulin resistance in adults, and the present paper therefore suggests that IUGR is related to impaired glucose metabolism during fetal development, which may cause type 2 diabetes in adulthood.

Hyperinsulinemia is closely related to low urinary clearance of D-chiro-inositol in men with a wide range of insulin sensitivity

We have previously shown that women with polycystic ovary syndrome (PCOS) have increased urinary clearance of D-chiro-inositol (uCl(DCI)), which was positively associated with hyperinsulinemia. The objective of this study was thus to determine if such relationship also exists in men with a large range of insulin sensitivity and levels. A cross-sectional study was performed on 11 brothers of women with PCOS and 21 control men. In this study, brothers served as a model of insulin resistance. We assessed uCl(DCI), urinary clearance of myo-inositol, and insulin levels with a standard 75-g oral glucose tolerance test, a 2-hour euglycemic-hyperinsulinemic clamp, and a 24-hour urine collection. Our results showed in all men together that low uCl(DCI) was strongly associated (P < .001) with hyperinsulinemia, for which uCl(DCI) was a significant predictor independent of other classic factors. Brothers were heavier than controls (P = .02), with increased glucose-stimulated glucose (P < .001) and insulin levels (P < .001) and reduced insulin sensitivity (P = .001). In this group, plasma DCI was increased by 3-fold (P = .02), with a 3-fold decrease in the uCl(DCI) to urinary clearance of myo-inositol ratio, which was almost significant (P = .07). Low uCl(DCI) is strongly associated with hyperinsulinemia in all men, and brothers of PCOS women who are more insulin resistant display increased plasma DCI and borderline decreased uCl(DCI). Thus, compensatory hyperinsulinemia might suppress renal clearance of DCI to increase plasma DCI levels and partially compensate for insulin resistance by improving DCI availability in men. The apparent discrepancy with PCOS women might be explained by higher insulin levels in men as compared with women and requires confirmation.