Reduced first-phase insulin secretion increases postprandial lipidemia in subjects with impaired glucose tolerance

Elevated triglyceride-glucose (TyG) index predicts impaired islet β-cell function: A hospital-based cross-sectional study

OBJECTIVE

To explore the relationship between the TyG index and the insulin secretion function of pancreatic β-cells, and to determine the possibility of the TyG index in predicting β-cell dysfunction and the development of diabetes.

METHODS

A cross-sectional study was performed among 914 participants who took their annual health checkups at the Third Xiangya Hospital. The early- and late-phase pancreatic β-cell secretion was assessed based on the results of the oral glucose tolerance test (OGTT). In addition to anthropometric parameters and laboratory parameters, information about health-related habits and disease histories was obtained from the National Physical Examination Questionnaire. Partial correlation analysis was used to study the relationship between the TyG index and pancreatic β-cell function. The receiver operating characteristic (ROC) curve was used to calculate the cut-off points of the TyG index in predicting β-cell dysfunction. According to the OGTT results and medical history, the participants were categorized into three groups: the normal glucose tolerance group (NGT, n=276), the impaired glucose regulation group (IGT, n=323), and the diabetes group (DM, n=315). The correlation between the TyG index and β-cell function among the three groups and the association between the TyG index and glucose metabolic conditions were further explored.

RESULTS

The TyG index was negatively correlated with the indexes that reflect the early and late secretory function of β-cells, not only in the NGT group but also in the IGT and DM group. The minimum cut-off values for the TyG index to identify the risk of early- and late-phase β-cell dysfunction are 9.08 and 9.2 respectively. The TyG indexes of the IGT and DM group were higher than that of the NGT group, and with the growth of the TyG index, the risk of prediabetes and diabetes increased significantly.

CONCLUSION

Increased TyG index is associated with impaired β-cell function regardless of the glucose metabolic conditions. The TyG index is an alternative indicator for predicting β-cell dysfunction.

Serum Uric Acid concentration is associated with insulin resistance and impaired insulin secretion in adults at risk for Type 2 Diabetes

AIMS

Insulin resistance (IR) predisposes to type 2 diabetes mellitus (T2DM). Although previous studies have associated serum uric acid concentration with IR in T2DM, its association with impaired insulin secretion and beta-cell dysfunction in subjects at risk for developing T2DM remains uncertain. Thus, we aimed to analyze the association of serum uric acid concentration with IR using surrogate insulin resistance/secretion and beta-cell function indices in subjects at risk for developing T2DM.

METHODS

This is a cross-sectional study that included 354 subjects who underwent an oral glucose tolerance test who had at least two risk factors for T2DM without any chronic disease.

RESULTS

Participants were 51±8 years old, 72.2% were women, had a mean body mass index of 29.9±6.5kg/m² and mean serum uric acid concentration of 5.7±1.3mg/dL. HOMA-IR, first-phase insulin secretion (S1Ph_OGTT), second-phase insulin secretion (S2Ph_OGTT), Matsuda and disposition indices were significantly correlated with serum uric acid concentrations (r=0.239, r=0.225, r=0.201, r=-0.287, r=-0.208; respectively). After multiple linear regression analysis, serum uric acid concentration was independently associated with HOMA-IR (β=0.283), HOMA-B (β=0.185), S1Ph_OGTT (β=0.203), S2Ph_OGTT (β=0.186), and Matsuda Index (β=-0.322). A serum uric acid concentration of 5.5mg/dL had the best sensitivity/sensibility to identify subjects with IR (HOMA-IR ≥2.5).

CONCLUSIONS

Serum uric acid concentration is significantly associated with IR and impaired insulin secretion, but not with beta-cell dysfunction, in subjects at risk for developing T2DM.