Hypoglycemia is the most common adverse effect of insulin therapy , including Levemir ( R ) , NovoLog ( R ) , and NovoLog ( R ) Mix 70 / 30 . As with all insulins , the timing of hypoglycemia may differ among various insulin formulations . Glucose monitoring is recommended for all patients with diabetes . Any change of insulin dose should be made cautiously and only under medical supervision . Changes in insulin strength , manufacturer , type , species , or method of manufacture may result in the need for a change in dosage .