Furthermore, it has been reported that there is a disorder of lipolysis in pancreatic islets of type 2 diabetic patients, and that inhibition of adipose triglyceride lipase (ATGL), which is a lipolytic enzyme, increases the size of lipid droplets and induces the deterioration of glucose-responsive insulin secretion [15], suggesting that intracellular lipid accumulation might also be associated with beta-cell dysfunction, resulting in glucose intolerance (Figure 1). Here, PNPLA2 is linked to type 2 diabetes mellitus.