Human Actrapid 40IU/ml Solution for Injection is used in the treatment of type 1 and 2 diabetes mellitus. This medicine works by suppressing the production of sugar in the liver and facilitates the reuptake of sugar in the fat and muscle cells, thereby maintaining consistent sugar control. Common side effects include low blood sugar, swelling in your hands or feet, weight gain, or thickening of the skin at the injection site.