Numbing creams that contain lidocaine are expensive and have some side effects and are not recommended for multiple daily injections.
Cold insulin right from the refrigerator can causes stinging when injected. It is fine to let your pen, or syringe warm up for 5 minutes, or, even the bottle of insulin for 5-10 minutes. Pinch up a fold of skin surrounding the site you've selected. Hold it firmly with one hand. You can inject insulin into muscle, but it is more painful. Inject into fat when possible. Inserting the needle. Faster is better, inserting slowly will cause more pain. Try inserting the needle almost like you would toss a dart. Needle angle. For adults or those with good fatty tissue, insert at a 90° angle. Thin adults and children may need to inject at a 45° angle. Try to get the needle all the way into fatty tissue below the skin, but not so deep that it hits the muscle below. Injecting the insulin. Push the syringe plunger all the way in with a slow steady motion or firmly press the insulin pen injection button. Wait ten seconds before removing the needle. Let go of the skin. Remove the needle by pulling straight out. Twisting or shifting the needle's position will cause pain. You may gently press on the injection site with your finger for a couple seconds. Do not rub or massage the skin where the insulin is injected; it can affect how fast the insulin is absorbed and acts within the body.