Introduction: A control of blood glucose is known to be the most important fact to protect development of complications of diabetes. A low-carbohydrate diet has been recognized to be one of the choices of diets for patients with diabetes. But, a very low-carbohydrate diet where the uptake of carbohydrate is lower than 130g per day is not recommended by American Diabetes Association now. Methods: We examined 16 patients who are continuing in some years a very low-saccharide diet where the uptake of saccharide is lower than 5g per diet. Results: Their fasting glucose, HbA1c, triglyceride, HDL-C, creatinine, all ionic values, pH and bicarbonate of venous blood were normal. Their ketone body and free fatty acid were higher than people who have normal diet, but their respiratory quotient was 0.72 and it assures their resource of energy changes from glucose to ketone body. Conclusion: Dietary ketosis never makes acidosis. The very low-saccharide diet is a safe and most effective diet for patients with diabetes.