The metallic taste in the mouth is caused by ketones, which is an acid the body produces when it breaks down fat for energy. This occurs when the body does not have enough insulin to use glucose, explains Diabetes.co.uk.
Ketosis is a normal metabolic process that occurs when there is not enough carbohydrates in the body for the cells to burn for energy. As a result, the body burns fat instead, according to WebMD, and this leaves an acid, or ketones.
While ketosis can be utilized as a weight-loss regime, high levels of ketones can poison the body, states the American Diabetes Association. People with diabetes should be aware of their ketones level, as when levels get too high, the individual can develop diabetic ketoacidosis, or DKA. Warning signs include thirst or a dry mouth, frequent urination, high blood glucose levels and high levels of ketones in the urine. These symptoms may then cause constant fatigue, dry or flushed skin, nausea or abdominal pain, breathing difficulties, a fruity odor in the breath, and/or difficulties in paying attention.
There are several ways to test for ketones at home, reports Diabetes.co.uk. The most accurate way is to use a blood glucose meter. Urine can also be tested for ketones. Ketones testing is especially important during pregnancy for those with Type 2 or gestational diabetes that is not treated with insulin.