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. [ABSTRACT FROM AUTHOR]