Biotin is a coenzyme and a B vitamin. It is also known as vitamin H. There isn’t a good laboratory test for detecting biotin deficiency, so this condition is usually identified by its symptoms, which include thinning of the hair (frequently with loss of hair color) and red scaly rash around the eyes, nose, and mouth. Nervous system symptoms include depression, exhaustion, hallucinations, and tingling of the arms and legs. There is some evidence that diabetes could result in biotin deficiency. Biotin supports the health of the skin, nerves, digestive tract, metabolism, and cells. Biotin may also help to treat some types of nerve pathology, such as the peripheral neuropathy that can result from kidney failure or diabetes. Biotin supplements have been studied as a treatment for a number of conditions. In people with type 2 diabetes, early research suggests that a combination of biotin and chromium might improve blood sugar. On its own, biotin might decrease insulin resistance and nerve symptoms related to type 2 diabetes.