Type 2 diabetes mellitus (DM2) is characterized by chronic hyperglycemia, which is a risk factor for comorbidities and death. Although conventional pharmacotherapy is effective, some individuals do not reach the glycemic targets, requiring adjuvant therapies. Taurine is a semi-essential amino acid with antioxidant and osmoregulatory properties, commonly used as a nutritional supplement. Pre-clinical studies show its effectiveness in reducing blood glucose and cholesterol, but there are no well-conducted clinical studies evaluating the effect of taurine on glycated hemoglobin. Additionally, animal models showed that taurine had a protective effect from diabetic nephropathy. The hypothesize of this study is that taurine administration improves the glycemic, lipid, inflammatory, and anthropometric parameters in DM2 individuals.

A randomized, double-blind, placebo-controlled clinical trial will be conducted at Hospital de Clínicas de Porto Alegre (HCPA), Brazil. A total of 94 participants with DM2 will be recruited and randomized on a 1:1 ratio to receive 3 g taurine as a powder for oral suspension, twice per day, for 12 weeks or packets containing placebo. Blood will be collected prior to the treatment and after 12 weeks for glycated hemoglobin, fasting glucose, insulinemia, total cholesterol and fractions, triglycerides, C-reactive protein, creatinine, urea, tumor necrosis factor-alpha (TNF-α), interleukin 1 and 6 (IL-1 and IL-6) measures. Urine will be collected at baseline and after 12 weeks for creatine, protein, and albumin measured. Anthropometric parameters and a 24-h dietary recall will be monthly investigated. Fourteen days before the end of the trial, participants will be connected to a continuous glucose monitoring system for glucose monitoring system for glucose variability evaluation. Participants will be contacted by phone weekly to report adverse effects.

Inclusion criteria

• Female and male individuals, with clinical diagnosis of DM2 for at least 6 months;
• Age over 30 years;
• BMC equal to or above 18.5 kg/m2, without weight change in the last 3 months;
• HbA1c between 7.5% and 10.5%.

Exclusion criteria

• Use of herbal supplements, antioxidants, and multivitamins in the last 3 months;
• Pregnancy or lactation;
• Chronic renal failure with glomerular filtration rate calculated by MDRD < 30 mL/h;
• Myocardial infarction in the last than 6 months
• Current neoplasia;
• Chronic use of glucocorticoids;
• Bariatric surgery.

The generation of the sequence of numbers will be done by a blinded researcher, after selecting the participant by the inclusion and exclusion criteria. The concealment of allocation will be implemented by a central randomization routine, conducted by researchers with access to the list and by the researcher responsible for requesting the code for placement of individuals in the study.