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Aims To investigate the effects of high-polyphenol chocolate upon endothelial function and oxidative stress in Type 2 diabetes mellitus during acute transient hyperglycaemia induced following a 75-g oral glucose challenge. Methods Ten subjects with Type 2 diabetes underwent a double-blinded randomized controlled crossover study. A 75-g oral glucose load was used to induce hyperglycaemia, which was administered to participants 60 min after they had ingested either low (control) or high-polyphenol chocolate. Participants undertook testing at weekly intervals, following an initial cocoa-free period. Endothelial function was assessed by both functional [reactive hyperaemia peripheral artery tonometry (EndoPAT-2000) and serum markers (including intercellular adhesion molecule 1, P-selectin and P-selectin glycoprotein ligand 1]. Urinary 15-F2t-isoprostane adjusted for creatinine was used as an oxidative stress marker. Measurements were made at baseline and 2 h post-ingestion of the glucose load. Results Prior consumption of high-polyphenol chocolate before a glucose load improved endothelial function (1.7 ± 0.1 vs. 2.3 ± 0.1%, P = 0.01), whereas prior consumption of control chocolate resulted in a significant increase in intercellular adhesion molecule 1 (321.1 ± 7.6 vs. 373.6 ± 10.5 ng/ml, P = 0.04) and 15-F2t-isoprostane (116.8 ± 5.7 vs. 207.1 ± 5.7 mg/mol, P = 0.02). Analysis of percentage changes from baseline comparing control and high-polyphenol chocolate showed a significant improvement for high-polyphenol chocolate in both measures of endothelial function ( P < 0.05) and for urinary 15-F2t-isoprostane ( P = 0.04). Conclusion High-polyphenol chocolate protected against acute hyperglycaemia-induced endothelial dysfunction and oxidative stress in individuals with Type 2 diabetes mellitus. [ABSTRACT FROM AUTHOR]

Background: Oxidative stress describes the cellular damage caused by excess reactive oxygen species not adequately inactivated by antioxidants. Oxidative stress has been implicated in playing a role in many disorders. Lipid peroxidation endproducts are employed as markers of oxidative stress, of which the isoprostane, 8-iso-PGF2α, is widely used. 8-iso-PGF2α is measured in plasma or urine by gas chromatography-mass spectrometry (GC/MS), liquid chromatography-mass spectrometry (LC/MS), tandem-mass spectrometry or enzyme-linked immunosorbent assay (ELISA). However, discrepancies between the specificity of these methods means correlation is poor. Methods: A tandem-mass spectrometric (LC/MS/MS) method, using immunoaffinity purification, for urinary 8-iso-PGF2α was developed and compared with two commercial ELISAs (A - Cayman Chemicals, B - Oxford Biomedical Research) in urine samples (n = 156). Results: An LC/MS/MS method coupled to immunoaffinity purification was developed with satisfactory performance and comparison to ELISAs A and B. Spearman rank correlation demonstrated significant correlation between all methods (P = <0.0001); however, r2 values ranged from 0.68 to 0.72. Bland-Altman plots revealed a proportional positive bias of ELISA B when compared with ELISA A and LC/MS/MS. Furthermore, the agreement between ELISA A and LC/MS/MS was poor. Conclusions: The poor agreement between methods for measurement of 8-iso-PGF2α highlights differences in selectivity. 8-iso-PGF2α is an isoprostane, a family of isomeric end-products of arachidonic acid peroxidation, which are produced by peroxidation or enzymatically. This makes avoiding cross-reactivity between 8-iso-PGF2α and related isomers challenging. When assessing oxidative stress studies, the selectivity of the methods used should be taken into account, particularly when comparing studies. [ABSTRACT FROM AUTHOR]

Women with polycystic ovary syndrome (PCOS) were found to have a higher biological variability in insulin resistance (IR) compared to controls, but it is unknown whether this variability in IR differs between PCOS who are anovulatory compared to those who have an ovulatory cycle. The primary aim of this study was to compare and contrast the variability of IR in women with ovulatory and anovulatory PCOS, in comparison to normal subjects. 53 Caucasian women with PCOS and 22 normal ovulating women were recruited. Fasting blood was collected each day on 10 consecutive occasions at 3–4 day intervals for analysis of insulin, glucose, progesterone, and testosterone. Analysis of progesterone levels showed 22 of 53 women with PCOS to have had an ovulatory cycle. Insulin resistance was calculated by HOMA method. Women with anovulatory PCOS had higher mean and variability of IR compared to those having an ovulatory cycle, and both were significantly higher than controls (mean�SEM; HOMA-IR 4.14�0.14 vs. 3.65�0.15 vs. 2.21�0.16, respectively) after adjustment or BMI. The mean BMI for individual PCOS patients correlated with mean HOMA-IR (p=0.009). Insulin resistance in women with anovulatory PCOS is both higher and more variable than in ovulatory PCOS. Since anovulatory PCOS therefore mimics the IR features of type 2 diabetes more closely, anovulation may be particularly associated with a higher cardiovascular risk compared to PCOS patients who ovulate. [ABSTRACT FROM AUTHOR]

The article offers the authors opinion on the role of haemoglobin A1c (HbA1c) as an important marker for long-term assessment of glycaemic control in patients with diabetes. They claim that HbA1c plays an important role in the management of diabetic patients and mainly assess their risk of developing microvascular and macrovascular complications. They supports their claim by referring to several studies like Diabetes Control and Complications Trial and the UK Prospective Diabetes Study.