Combining regular exercise and a healthy diet is recommended in international guidelines to fight type 2 diabetes mellitus (T2DM). Low- and very low-carbohydrate diets have attracted attention in the last years. This article takes a critical look at the possible effects when regular exercise and carbohydrate restriction are combined. An increased intervention effect on the oxidative capacity as well as glucose and lipid profiles can be assumed (at least for a short period of time). However, anabolic signaling pathways might be blunted during a very low-carbohydrate diet and increasing ketosis. Thus, muscle build-up can become difficult or impossible. Furthermore, maximal performance during high-intensity workouts may be attenuated due to a possible reduced anaerobic glycolysis and metabolic inflexibility in T2DM patients. However, more studies are needed to evaluate the effects of this combination in comparison to those of exercise and other types of diet.