Hi, Novomix30 is an analogue insulin where as human mixtard 30 is human insulin. Although both are premixed insulins which means they are a combination of 2 different types of insulin which contain short/ rapid acting insulin and a long acting insulin, they vary in their pharmacokinetic profile and research studies show that analogue insulins closely mimic the insulin needs of the body than human insulins. With human insulin preparations the risk of hypoglycaemia( low sugar) is slightly higher compared to analogue insulins. Analogue insulins are slightly expensive than human insulin preparations. In your case if your sugars are better controlled on novomix30 you can discuss with your diabetologist regarding the dosing and dosage required and change it to analogues or novomix 30 from human mixtard 30.