Serum gamma-glutamyltransferase levels are related to insulin sensitivity and secretion in subjects with abnormal glucose regulation

Potential role of liver enzyme levels as predictive markers of glucose metabolism disorders in a Tunisian population

The relationship between liver enzymes and T2D risk is inconclusive. We aimed to evaluate the association between liver markers and risk of carbohydrate metabolism disorders, as well as their discriminatory power, for T2D prediction. This cross-sectional study enrolled 216 participants classified as normoglycemic, prediabetic, newly diagnosed diabetics, and diagnosed diabetics. All participants underwent anthropometric and biochemical measurements. The relationship between hepatic enzymes and glucose metabolism markers was evaluated by analyses of covariance. The associations between liver enzymes and incident carbohydrate metabolism disorders were analyzed through logistic regression and their discriminatory capacity to predict T2D by ROC analysis. High AP, ALT, γGT, and AST levels were independently related to decreased insulin sensitivity. Interestingly, a higher AP level was significantly associated with an increased risk of prediabetes (p = 0.017), newly diagnosed diabetes (p = 0.004), and T2D (p = 0.007). An elevated γGT level was an independent risk factor for T2D (p = 0.032) and undiagnosed T2D (p = 0.010) in prediabetic and normoglycemic subjects, respectively. In ROC analysis, AP was a powerful predictor of incident diabetes and significantly improved T2D prediction. Liver enzymes within the normal range, specifically AP levels, are associated with increased risk of carbohydrate metabolism disorders and significantly improved T2D prediction.

Potential impact of joint association of alanine aminotransferase and gamma-glutamyltransferase on insulin resistance in Japan: The Toranomon Hospital Health Management Center Study 19 (TOPICS 19)

AIM

To investigate the potential impact of joint association of alanine aminotransferase (ALT) and γ-glutamyltransferase (GGT) on insulin resistance and β-cell dysfunction in healthy Japanese individuals with a normal range of liver enzymes.

METHODS

This study included 1010 individuals (545 men and 465 women) aged 20-89 years who underwent an oral glucose tolerance test for health screening. Participants were divided into four groups on the basis of median values for ALT and GGT: (i) both ALT and GGT low (both-low); (ii) ALT high and GGT low (ALT-high); (iii) ALT low and GGT high (GGT-high); and (iv) both ALT and GGT high (both-high). Logistic regression analysis was used to investigate the relationship between liver enzyme and insulin dynamics, such as Homeostasis Model of Assessment - Insulin Resistance (HOMA-IR) and insulinogenic index (IGI). The insulin resistance was defined when HOMA-IR was 2.5 or more. IGI of less than 0.4 was considered to be decreased early-phase insulin secretion.

RESULTS

Mean values of HOMA-IR in men was 1.5 in the both-low group, 1.8 in ALT-high, 1.8 in GGT-high and 2.8 in both-high. The mean HOMA-IR in women was 1.3 in the both-low group, 1.3 in ALT-high, 1.6 in GGT-high and 2.0 in both-high. HOMA-IR in the both-high group was significantly higher than that in the both-low group regardless of the difference of sex. Multivariate analysis showed that insulin resistance occurred when the patient had high liver enzymes.

CONCLUSION

Combining the two liver function markers would be effective for identifying individuals with insulin resistance.

Serum Gamma-glutamyltransferase Levels Predict the Progression of Coronary Artery Calcification in Adults With Type 2 Diabetes Mellitus

Progression of coronary artery calcification (CAC) may be more predictive of future coronary heart disease events than a baseline CAC score. We determined whether serum gamma-glutamyltransferase (GGT) activity can independently predict the progression of CAC in adults with type 2 diabetes mellitus (T2DM). Patients (n = 326) without symptomatic cardiovascular (CV) disease were evaluated by CAC imaging. The CAC scores were assessed at baseline and after 20 ± 4 months. Serum GGT activities were significantly higher in progressors compared with nonprogressors (39 ± 16 vs 27 ± 11 U/L, P < .001). Multivariable analyses demonstrated that GGT activity retained a strong association with CAC progression after adjustment for CV risk factors. Additionally, there was a graded association between GGT activity quartile and annualized CAC progression. In asymptomatic patients with T2DM, we prospectively found that serum GGT activity may be an independent predictor of CAC progression but not a predictor of CAC incidence.

The association of gamma-glutamyltransferase and C-reactive protein with IFG/IGT in Chinese adults in Qingdao, China

BACKGROUND

Serum gamma-glutamyltransferase (GGT) and C-reactive protein(CRP) have been previously shown to be associated with impaired fasting glucose/impaired glucose tolerance (IFG/IGT), but such an association has not been well verified, and is examined in a non-diabetic Chinese population.

METHODS

A population-based cross-sectional study was conducted in 2006 in Qingdao, China. Data of 1143 men and 1689 women aged 35-74 years and free of diabetes at baseline were analyzed. Multivariable logistic regression analysis was performed to estimate the odds ratio (OR) and its 95% confidence interval (CI).

RESULTS

Compared with the lowest quartile, the ORs (95%CI) for IFG/IGT corresponding to the highest quartile were 0.89(0.61,1.28) in men and 0.87(0.64,1.18) in women for CRP and 2.12(1.40,3.38) and 1.87(1.32,2.62) for GGT, when the two were fitted simultaneously in a model adjusting for age, school years, alcohol-drinking, smoking, family history of diabetes, systolic blood pressure, waist circumference, triglycerides and high-density lipoprotein.

CONCLUSIONS

The elevated GGT, but not CRP, was independently associated with the presence of the IFG/IGT in both genders in this Chinese population.