Multicenter, randomized, double-blind, placebo-controlled, parallel group study to assess the efficacy and safety of treatment with metformin at a dose of 1700 mg / day in adults with HD.~A total recruitment of 60 patients is expected, which will be randomized in a 1: 1 ratio. 30 patients will receive metformin 1700 g / day, or placebo, for 52 weeks.~Patients will begin taking low doses of metformin, to facilitate tolerance and decrease intestinal discomfort. Half the daily dose (425 mg twice daily) will be administered over four weeks, along with the main meals. Patients who tolerate this dose well will continue with treatment by taking 850mg twice daily. Patients who don´t tolerate the initial dose (425 mg twice daily) will be withdrawn from the study.
Multicenter, randomized, double-blind, placebo-controlled, parallel group study to assess the efficacy and safety of metformin treatment at a dose of 1700 mg / day in adults with Huntington's disease.~The study consists of a screening period (2 to 4 weeks), followed by a 52-week double-blind treatment period and a follow-up visit (one month after the end of treatment).