GCG and type 2 diabetes mellitus: A recent systematic review and meta-analysis of 9 RCTs examining the effects of almonds on gut microbiota, glucose metabolism and inflammatory parameters in T2DM reported that almond-based diets have significant effects in promoting the growth of short-chain fatty acid-producing gut microbiota, and lower HbA1c and body weight, but with no observed differences on the levels of fasting or 2-h postprandial blood glucose, inflammatory markers (C-reactive protein and tumour necrosis factor- α), GLP-1, fasting blood insulin, and IR [423].