BackgroundTo determine whether the TyG index, a product of the levels of triglycerides and fasting plasma glucose (FPG) might be a valuable marker for predicting future diabetes.MethodsA total of 5,354 nondiabetic subjects who had completed their follow-up visit for evaluating diabetes status were selected from a large cohort of middle-aged Koreans in the Chungju Metabolic Disease Cohort study. The risk of diabetes was assessed according to the baseline TyG index, calculated as ln[fasting triglycerides (mg/dL) × FPG (mg/dL)/2]. The median follow-up period was 4.6 years.ResultsDuring the follow-up period, 420 subjects (7.8%) developed diabetes. The baseline values of the TyG index were significantly higher in these subjects compared with nondiabetic subjects (8.9±0.6 vs. 8.6±0.6; P<0.0001) and the incidence of diabetes increased in proportion to TyG index quartiles. After adjusting for age, gender, body mass index, waist circumference, systolic blood pressure, high-density lipoprotein (HDL)-cholesterol level, a family history of diabetes, smoking, alcohol drinking, education level and serum insulin level, the risk of diabetes onset was more than fourfold higher in the highest vs. the lowest quartile of the TyG index (relative risk, 4.095; 95% CI, 2.701–6.207). The predictive power of the TyG index was better than the triglyceride/HDL-cholesterol ratio or the homeostasis model assessment of insulin resistance.ConclusionsThe TyG index, a simple measure reflecting insulin resistance, might be useful in identifying individuals at high risk of developing diabetes.

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We present the results of a study of the interactions between three different acid-terminated self-assembled monolayer (SAM) surfaces and three basic vapor-phase probe molecules. The SAMs are composed of 4-mercaptobenzoic acid (MBA), 3-mercaptopropionic acid (MPA), and 11-mercaptoundecanoic acid (MUA), and the vapor-phase probes are, in order of increasing solution-phase acidity, decylamine, pyridine, and pyrazine. Our results are based on data from surface infrared spectroscopy and thickness-shear mode mass sensors. We find that all three SAMs irreversibly bind approximately one monolayer of decylamine, although there are slight differences that correlate with the structural nuances of the SAMs. The MPA and MBA SAMs bind decylamine through an electrostatic interaction brought about by transfer of a proton from the acid to the base. Because the MUA SAM is more impenetrable than the others, complete proton transfer is hindered, and binding of decylamine arises through a combination of proton transfer and strong hydrogen bonding. In the presence of its vapor, pyridine adsorbs to MBA surfaces at near-monolayer coverage, but upon N2 purging about two-thirds of it desorbs. Only one-half monolayer of pyrazine, which is less basic than pyridine, adsorbs to the MBA SAM, and upon N2 purging, about two-thirds of it desorbs. The aliphatic acid SAMs follow a similar trend. The results of this study indicate that the extent of base binding correlates most strongly with the structural nuances of the acidic SAMs and the relative basicity of the vapor-phase bases. These results are relevant to SAM-based chemical sensors.

We used Fourier transform infrared external reflectance spectroscopy (FTIR-ERS), nanogravimetry based on thickness-shear-mode resonators (TSMRs), and X-ray photoelectron spectroscopy (XPS) to study self-assembled monolayers (SAMs) of three mercaptobenzoic acid (MBA) isomers on Au and their interactions with vapor-phase decylamine. FTIR-ERS spectra of the 4-, 3-, and 2-MBA SAMs indicate that the proximity of the carboxylic acid group to the Au substrate surface affects the electronic environment of the benzene ring and the acidity of the carboxyl-group proton. TSMR results show that reaction of 4-, 3-, and 2-MBA monolayers with vapor-phase decylamine probe molecules results in decylamine fractional surface coverages of 0.97, 0.83, and 0.45 of the theoretical monolayer maximum, respectively. The gravimetric results are corroborated by in- situ FTIR-ERS difference spectra of the MBA monolayers obtained during reaction with decylamine, which show the simultaneous disappearance of carbonyl and hydroxyl bands and appearance of carboxylate and aliphatic hydrocarbon bands. XPS results show that increasing the proximity of the carboxyl group to the surface results in a relative increase in the proportion of carboxyl-group oxygen that is in the 531.0 eV electron binding energy state compared to the 532.5 eV state, indicating a change of chemical environment for oxygen. The overall results are consistent with a model involving proton transfer from the SAM to the vapor-phase bases wherein acid strength depends on the accessibility of the donor group, and they demonstrate a clear structure/reactivity correlation for surface-confined isomers, which illustrates the dramatic constraints imposed by surface-induced ordering compared to anisotropic bulk-phase reactivity.