Since the 1990s, people with type 1 diabetes have been advised they can eat what they like as long as they inject an appropriate amount of insulin. Many find this does not work, and often experience postprandial hyperglycaemia. A high carbohydrate intake requires a high insulin dosage which carries health risks including weight gain and insulin resistance. Increasingly, patients are choosing to restrict their carbohydrate intake and a number of studies have shown this can help reduce HbA1c, increase glucose time in range and reduce hypoglycaemia. There is no evidence that nutritional ketosis increase the risk of ketoacidosis. Patients who wish to choose carbohydrate restriction should be supported by their diabetes health professionals with appropriate advise on reducing insulin doses.