There has been an increasing amount of information about the positive results of low-carbohydrate diet in the treatment of diabetes, pre-diabetes, metabolic syndrome and obesity in the form of randomized trials, their meta-analysis and case studies. Many of these indicate that low carbohydrate diets are safe, could significantly improve the compensation of both types of diabetes and the overall health of the diabetic patients. In successful therapy, this diet leads to weight loss, lower medication doses or prescribing, and in some cases of type 2 diabetes also to remission. However, the low carbohydrate diet is not recognized in Czech diabetology, and concerns remain particularly about its safety. This article is a summary of the current knowledge about low-carbohydrate diet, its benefits, risks and contraindications, and aims to initiate a discussion about its use as one of the options for dietary treatment of diabetics. Key words: diabetes mellitus - ketogenic diet - low-carbohydrate diet - metabolic syndrome - obesity.