Abstract: Provided herein are methods for modulating the intestinal microbial profile and for reducing intestinal dysbiosis in type 2 diabetic or pre-diabetic subjects, comprising administering metformin or a derivative or salt thereof and one or more probiotic microorganisms selected from Lactobacillus plantarum, Lactobacillus bulgaricus, Lactobacillus gasseri, Bifidobacterum breve, Bifidobacterium animalis subsp. lactis, Bifidobacterium bifidum, Streptococcus thermophilus and Saccharomyces boulardii. Also provided are methods for treating type 2 diabetes or an associated metabolic complication or condition and for delaying the onset of type 2 diabetes in pre-diabetic subjects, comprising administering one or more probiotic microorganisms selected from Lactobacillus plantarum, Lactobacillus bulgaricus, Lactobacillus gasseri, Bifidobacterum breve, Bifidobacterium animalis sub sp. lactis, Bifidobacterium bifidum, Streptococcus thermophilus and Saccharomyces boulardii.

Abstract: Provided herein are methods for diagnosing pre-diabetes or type 2 diabetes based on faecal or colonic samples and determining levels of butyric acid and one or both or acetic acid and propionic acid in the samples, and thereby determining the molar ratio of acetic acid to butyric acid, propionic acid to butyric acid and/or acetic acid to propionic acid to butyric acid. Also provided are methods for increasing the intestinal, colonic or faecal molar ratio of acetic acid to butyric acid, the intestinal, colonic or faecal molar ratio of propionic acid to butyric acid and/or the intestinal, colonic or faecal molar ratio of acetic acid to propionic acid to butyric acid in subjects with type 2 diabetes.