Study aims to ascertain body mass index cutoffs for type 2 diabetes in Xinjiang population

Oncotarget published "Appropriate body mass index cutoffs for type 2 diabetes in Xinjiang population: defining the influence of liver aminotransferase" which reported that these authors retrospective cohort study, T2DM was diagnosed when FBS ≥ 7.0 mmol/L, BMI of participants with baseline fasting < 7.0 mmol/L was divided by percentiles and by aminotransferanse .

Hazard ratios and the turning point of BMI of high T2DM risk was estimated in totality and different aminotransferanse groups.

During an average follow-up time of 3.71 years of 33346 participants, 1486 developed T2DM, and the average baseline BMI of participants who developed T2DM was 26.22 kg/m2. Cumulative incidence of T2DM was more than 5% when ALT and AST ≥ 20U/L, age over 44, male sex or BMI over 25.39 kg/m2; The risk of T2DM incidence increased as the BMI grow.

The turning point of BMI at high risk of T2DM was 25.0 kg/m2 in totality, 25.1 kg/m2 when ALT or AST < 20 U/L and 26.1 kg/m2 when ALT and AST ≥ 20U/L.

BMI of 25.0 kg/m2 was the cutoff point for T2DM development, and there is greater association between BMI and T2DM when ALT or AST < 20 U/L.

Dr. Xiao-Lan Lu from The Second Affiliated Hospital of Xi'an Jiaotong Universityas well as The Shanghai Pudong Hospital of Fudan University and Dr. Yong Shao from The Community Health Service Center of Jinxi Town said, "Type 2 diabetes (T2DM) is one of the most serious public health issues in the 21st century and is becoming increasingly prevalent worldwide."

According to the national survey of obesity and metabolic syndrome, the average BMI in T2DM patients is 25.0 kg/m2, the prevalence of T2DM in BMI from 25.0 kg/m2 to 27.4 kg/m2 and above 27.4 kg/m2 is 12.8% and 18.5%, the prevalence in male adult is 33.7% and 13.7%, and that in female adult is 29.2% and 10.7%, respectively.

A study based on Thai population derived the BMI cut-point to define T2DM risk by odds ratio as 22; Another multicenter research found BMI of 25 kg/m2 in Chinese is equivalent of BMI of 24 kg/m2 in South Asian for incidence rate of diabetes.

Liver dysfunction is also associated with T2DM, and the association between serum alanine aminotransferase, aspartate aminotransferase and T2DM was broadly replicated.

Another study further indicated that T2DM risk attributed to BMI could be influenced by liver aminotransferase: in group of high levels of both AST and ALT and in group of high level of either AST or ALT, high BMI was independently associated with diabetes incidence, and in group of high levels of both AST and ALT, odds ratio was relatively higher than that in group of high levels of either AST and ALT; While in group of low levels of both AST and ALT, high BMI was not an independent risk factor for diabetes.

In this study, the authors aimed to find the cut-off point of BMI associated with high T2DM risk in Xinjiang population; "we also aimed to find the difference of cut-off point brought by elevated liver aminotransferase".

The Lu Research Team concluded in their Oncotarget Research Output that studies have proved that among the most studied clinical liver serum biomarkers, higher serum AST or ALT is associated with higher T2DM risk.

In this study, they set 19 U/L as a healthy limit for participants and set aminotransferase group 1 as higher level for both AST and ALT. In our study, the rise of both AST and ALT was an independent risk factor of T2DM.

Since serum AST and ALT are markers of non-alcoholic fatty liver disease, which is a strong independent risk factor of T2DM, this finding can be explained.

Elevated serum AST and ALT alone could also increase the risk of T2DM, and is independent of NAFLD.

BMI in group 2 showed higher association with T2DM compared with group 1.

Also, the cut-off point of BMI in group 1 is higher than that in group 2, indicating a greater relationship of BMI and T2DM in group 2, probably because of insulin resistance caused by liver dysfunction.