INS and metabolic disease: From 59 T2D patients, high-carbohydrate, high-fat, and high-protein diets were found to increase counts of Clostridium clusters IV and XI and decreased counts of Bifidobacterium species, order Lactobacillales, and Clostridium cluster IV in gut; therefore, fecal short-chain fatty acid (SCFA) production was decreased subsequently, leading to metabolic disorders, which increased the blood insulin levels and insulin resistance (Yamaguchi et al., 2016).