Drug therapy Patients with type 1 DM require insulin therapy for blood glucose control and may use other antidiabetic drugs, as well Antidiabetic drugs are not a substitute for dietary modification and exercise. Teach the patient about continuing dietary changes and regular exercise while taking antidiabetic drugs. Metformin, a biguanide, decreases liver glucose production and decreases intestinal absorption of glucose. It also improves insulin sensitivity, which increases peripheral glucose uptake and utilization. Continuous subcutaneous infusion of a basal dose of insulin (CSII) with additional insulin at mealtimes is more effective in controlling blood glucose levels than other schedules. It allows flexibility in meal timing, because if a meal is skipped, the additional mealtime dose of insulin is not given Patient education: drugs. To prevent loss of drug potency, teach the patient to avoid exposing insulin to temperatures below 36°F or above 86°F , to avoid excessive shaking, and to protect insulin from direct heat and light. Insulin should not be allowed to freeze. Teach patients to discard any unused insulin after 28 days. Teach patients to always have a spare supply of each type of insulin used. Prefilled syringes are stable for up to 30 days when refrigerated. Proper dose preparation is critical for insulin effectiveness and safety. Teach patients that the person giving the insulin needs to inspect the vial before each use for changes (e.g., clumping, frosting, precipitation, or change in clarity or color) that may indicate loss in potency Other insulins should be clear. If potency is questionable, another vial or pen of the same insulin type should be used