gamma-Glutamyl-transpeptidase in diabetics: a case control study

An Inverse Association between Serum Gamma Glutamyl Transpeptidase Activity and Breslow's Lifestyle Index; Its Practical Application for Screening of Subjects with Unhealthy Lifestyles

We examined whether serum gammaGTP activity (gammaGTP) is associated with Breslow's lifestyle index and whether it could be used as a tool to detect subjects with unhealthy lifestyles. To that effect, 724 male Japanese workers excluding patients suffering from hepatitis virus infection, autoimmune liver diseases and apparently active bile duct diseases were cross-sectionally examined. gammaGTP was inversely associated with the total score of Breslow's index for all subjects (lambda=30.643) and in subjects aged 40 or more (lambda=37.073). The association was consistent even after adjustments of subjects' ages and levels of triglycerides, total cholesterol and uric acid (p=0.0001). Among the seven lifestyle factors comprising Breslow's index, improper habits of drinking (p<0.0001), smoking (p=0.0204), exercise (p=0.0189) and body weight control (p<0.0001), were associated with increased gammaGTP. Even in a survey in which subjects who had proper habits of drinking and body weight control were selectively examined, improper habits of smoking and exercise still tended to be associated with increased gammaGTP. Receiver operating characteristic curves indicated that gammaGTP was beneficial for detecting subjects who scored two or less on Breslow's index, at least in subjects aged 40 or more. gammaGTP was associated with insulin resistance level estimated by the homeostasis model assessment (p<0.0001), which was inversely associated with Breslow's index (p=0.0040). gammaGTP could be used as an objective substitute of Breslow's index, allowing us to identify subjects with low scores on Breslow's index, at least after sorting subjects properly. Such screening would enable interventions to correct subjects' unhealthy lifestyles, helping to solve lifestyle-related disease issues.

Association between gamma-glutamyl transpeptidase activity and status of disorders constituting insulin resistance syndrome

BACKGROUND

Serum gamma-glutamyl transferase (gamma GTP) activity is a well-established marker of alcohol consumption. However, recently, a correlation between serum gamma GTP activity and insulin resistance status has been demonstrated.

METHODS

To determine whether serum gamma GTP activity could be associated with the status of various disorders caused by increased insulin resistance levels, namely, insulin resistance syndrome, a cross-sectional study for 11,884 Japanese men was performed. They were divided into three groups by their age, and associations between gamma GTP and various indexes of insulin resistance syndrome were studied by multiple logistic regression analysis in which subjects' drinking styles were corrected for in each age bracket.

RESULTS

Consuming ethanol more than 40 g/day, body mass index more than 25.9 kg/m2, and triglyceride levels more than 150 mg/dl were significant risk factors accounting for increased gamma GTP activity (more than 78 IU/liters) irrespective of age. In addition, when subjects of 40 to 59 years old were selectively studied, hypertension, hypercholesteremia, hyperuricemia, and increased glycohemoglobin A1C levels were also significant risk factors for increased gamma GTP activity.

CONCLUSIONS

There are significant associations between gamma GTP and the status of insulin resistance syndrome. In addition to excessive alcohol consumption, the status of insulin resistance syndrome could affect subjects' gamma GTP activities.

Gamma glutamyl transferase

Serum gamma-glutamyl transferase (GGT) has been widely used as an index of liver dysfunction and marker of alcohol intake. The last few years have seen improvements in these areas and advances in understanding of its physiological role in counteracting oxidative stress by breaking down extracellular glutathione and making its component amino acids available to the cells. Conditions that increase serum GGT, such as obstructive liver disease, high alcohol consumption, and use of enzyme-inducing drugs, lead to increased free radical production and the threat of glutathione depletion. However, the products of the GGT reaction may themselves lead to increased free radical production, particularly in the presence of iron. There have also been important advances in the definition of the associations between serum GGT and risk of coronary heart disease, Type 2 diabetes, and stroke. People with high serum GGT have higher mortality, partly because of the association between GGT and other risk factors and partly because GGT is an independent predictor of risk. This review aims to summarize the knowledge about GGT's clinical applications, to present information on its physiological roles, consider the results of epidemiological studies, and assess how far these separate areas can be combined into an integrated view.