The number of people affected by type 2 diabetes (i.e. high blood glucose levels) is increasing rapidly. In this thesis I investigated the role of human brown fat in the development and treatment of this disease. Brown fat is activated upon exposure to cold, and its main function in the human body is to produce heat by means of oxidation of fats and carbohydrates.

My data shows that prolonged exposure to mild cold temperatures enhances brown fat volume and activity in both obese individuals as well as patients with type 2 diabetes. Surprisingly, prolonged cold exposure also induced adaptations in skeletal muscle, which led to improved whole-body insulin sensitivity. As reduced insulin sensitivity is the main cause for the development of type 2 diabetes, these data unravel a completely new physiological means (i.e. cold exposure) for prevention and treatment of type 2 diabetes and associated metabolic conditions.