Objective To estimate the global burden of type 2 diabetes in adolescents and young adults (aged 15-39 years) from 1990 to 2019. Design Systematic analysis. Data source Global Burden of Disease Study 2019. Participants aged 15-39 years from 204 countries and territories, 1990-2019. Main outcomes measures Age standardised incidence rate, age standardised disability adjusted life years (DALY) rate, and age standardised mortality rate for type 2 diabetes in people aged 15-39 years from 1990 to 2019, and proportional DALY attributable to different risk factors. Results From 1990 to 2019, significant increases in age standardised incidence rate and age standardised DALY rate were found for type 2 diabetes in adolescents and young adults globally (P<0.001). Age standardised incidence rate (per 100 000 population) increased from 117.22 (95% confidence interval 117.07 to 117.36) in 1990 to 183.36 (183.21 to 183.51) in 2019, and age standardised DALY rate (per 100 000 population) increased from 106.34 (106.20 to 106.48) in 1990 to 149.61 (149.47 to 149.75) in 2019. The age standardised mortality rate (per 100 000 population) was modestly increased from 0.74 (0.72 to 0.75) in 1990 to 0.77 (0.76 to 0.78) in 2019. When grouped by countries with different sociodemographic indexes, countries with a low-middle and middle sociodemographic index had the highest age standardised incidence rate and age standardised DALY rate in 2019, whereas countries with a low sociodemographic index had the lowest age standardised incidence rate but the highest age standardised mortality rate. Women generally had higher mortality and DALY rates than men at ages 30 years except in countries with a low sociodemographic index. The main attributable risk factor for DALY for early onset type 2 diabetes was high body mass index in all regions by sociodemographic index. The proportional contribution of other risk factors varied across regions, however, with higher proportions of ambient particulate air pollution and smoking in countries with a high sociodemographic index and higher proportions of household air pollution from solid fuels and diet low in fruit in countries with a low sociodemographic index. Conclusions Early onset type 2 diabetes is a growing global health problem in adolescents and young adults, especially in countries with a low-middle and middle sociodemographic index. A greater disease burden in women aged <30 years was found. Specific measures are needed in countries with different levels of socioeconomic development because of the variable attributable risk factors for type 2 diabetes in adolescents and young adults.

The effect of acetic acid on hepatic lipid metabolism in ruminants differs significantly from that in monogastric animals. Therefore, the aim of this study was to investigate the regulation mechanism of acetic acid on the hepatic lipid metabolism in dairy cows. The AMP-activated protein kinase (AMPK) signaling pathway plays a key role in regulating hepatic lipid metabolism. In vitro, bovine hepatocytes were cultured and treated with different concentrations of sodium acetate (neutralized acetic acid) and BML-275 (an AMPKα inhibitor). Acetic acid consumed a large amount of ATP, resulting in an increase in AMPKα phosphorylation. The increase in AMPKα phosphorylation increased the expression and transcriptional activity of peroxisome proliferator-activated receptor α, which upregulated the expression of lipid oxidation genes, thereby increasing lipid oxidation in bovine hepatocytes. Furthermore, elevated AMPKα phosphorylation reduced the expression and transcriptional activity of the sterol regulatory element-binding protein 1c and the carbohydrate responsive element-binding protein, which reduced the expression of lipogenic genes, thereby decreasing lipid biosynthesis in bovine hepatocytes. In addition, activated AMPKα inhibited the activity of acetyl-CoA carboxylase. Consequently, the triglyceride content in the acetate-treated hepatocytes was significantly decreased. These results indicate that acetic acid activates the AMPKα signaling pathway to increase lipid oxidation and decrease lipid synthesis in bovine hepatocytes, thereby reducing liver fat accumulation in dairy cows.