Insulin is a hormone that works by lowering levels of glucose (sugar) in the blood. Insulin lispro is a fast-acting insulin. Insulin lispro protamine is an intermediate-acting insulin. This combination insulin starts to work within 10 to 20 minutes after injection, peaks in 2 hours, and keeps working for up to 24 hours.

Humalog Mix 50/50 is a combination medicine used to improve blood sugar control in adults with diabetes mellitus. Humalog Mix 50/50 may be used for type 1 or type 2 diabetes.

Humalog Mix 50/50 may also be used for purposes not listed in this medication guide.

Never share an injection pen, cartridge, or syringe with another person, even if the needle has been changed.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Use the medicine exactly as directed.

Insulin is injected under the skin. A healthcare provider can teach you how to properly use the medication by yourself. Do not inject Humalog Mix 50/50 into a vein.

Use this medication within 15 minutes before eating a meal.

If you use an injection pen, use only the injection pen that comes with Humalog Mix 50/50. Attach a new needle before each use. Do not transfer the insulin from the pen into a syringe.

Your care provider will show you the best places on your body to inject this insulin. Use a different place each time you give an injection. Do not inject into the same place two times in a row.

Do not inject this medicine into skin that is damaged, tender, bruised, pitted, thickened, scaly, or has a scar or hard lump.

Never share an injection pen, cartridge, or syringe with another person, even if the needle has been changed. Sharing these devices can allow infections or disease to pass from one person to another.

Use a disposable needle and syringe only once. Follow any state or local laws about throwing away used needles and syringes. Use a puncture-proof "sharps" disposal container (ask your pharmacist where to get one and how to throw it away). Keep this container out of the reach of children and pets.

You may have low blood sugar (hypoglycemia) and feel very hungry, dizzy, irritable, confused, anxious, or shaky. To quickly treat hypoglycemia, eat or drink a fast-acting source of sugar (fruit juice, hard candy, crackers, raisins, or non-diet soda).

Your doctor may prescribe a glucagon injection kit in case you have severe hypoglycemia. Be sure your family or close friends know how to give you this injection in an emergency.

Also watch for signs of high blood sugar (hyperglycemia) such as increased thirst or urination.

Blood sugar levels can be affected by stress, illness, surgery, exercise, alcohol use, or skipping meals. Ask your doctor before changing your dose or medication schedule.

Insulin is only part of a complete treatment program that may also include diet, exercise, weight control, regular blood sugar testing, and special medical care. Follow your doctor's instructions very closely.

Keep this medicine in its original container protected from heat and light. Do not draw insulin from a vial into a syringe until you are ready to give an injection. Do not freeze insulin or store it near the cooling element in a refrigerator. Throw away any insulin that has been frozen.

Storing unopened (not in use) Humalog Mix 50/50:

• Refrigerate and use until expiration date; or

• Store at room temperature and use the vial within 28 days or use the injection pen within 10 days.

Storing opened (in use) Humalog Mix 50/50:

• Store the vial in a refrigerator or at room temperature and use within 28 days.

• Store the injection pen at room temperature (do not refrigerate) and use within 10 days. Do not store the injection pen with a needle attached.

This medicine should look cloudy. Do not use the medicine if it looks clear or has particles in it. Call your pharmacist for new medicine.

In case of emergency, wear or carry medical identification to let others know you have diabetes.

You should not use this medicine if you are allergic to insulin lispro, or if you are having an episode of hypoglycemia (low blood sugar).

Humalog Mix 50/50 is not approved for use by anyone younger than 18 years old.

Tell your doctor if you have ever had:

• liver or kidney disease; or

• low levels of potassium in your blood (hypokalemia).

Tell your doctor if you also take pioglitazone or rosiglitazone (sometimes contained in combinations with glimepiride or metformin). Taking certain oral diabetes medicines while you are using insulin may increase your risk of serious heart problems.

Tell your doctor if you are pregnant or breastfeeding.

Follow your doctor's instructions about using insulin if you are pregnant or you become pregnant. Controlling diabetes is very important during pregnancy, and having high blood sugar may cause complications in both the mother and the baby.

Since Humalog Mix 50/50 is used before meals, you may not be on a timed dosing schedule. Whenever you use the medicine, be sure to eat a meal within 15 minutes. Do not use two doses at one time.

Keep insulin on hand at all times. Get your prescription refilled before you run out of medicine completely.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. Insulin overdose can cause life-threatening hypoglycemia. Symptoms include drowsiness, confusion, blurred vision, numbness or tingling in your mouth, trouble speaking, muscle weakness, clumsy or jerky movements, seizure (convulsions), or loss of consciousness.

Insulin can cause low blood sugar. Avoid driving or operating machinery until you know how this medicine will affect you.

Avoid medication errors by always checking the medicine label before injecting your insulin.

Avoid drinking alcohol. It can cause low blood sugar and may interfere with your diabetes treatment.

Get emergency medical help if you have signs of insulin allergy: redness or swelling where an injection was given, itchy skin rash over the entire body, trouble breathing, fast heartbeats, feeling like you might pass out, or swelling in your tongue or throat.

Humalog Mix 50/50 may cause serious side effects. Call your doctor at once if you have:

• fluid retention--weight gain, swelling in your hands or feet, feeling short of breath; or

• low potassium--leg cramps, constipation, irregular heartbeats, fluttering in your chest, increased thirst or urination, numbness or tingling, muscle weakness or limp feeling.

Common side effects of Humalog Mix 50/50 may include:

• low blood sugar;

• itching, mild skin rash; or

• thickening or hollowing of the skin where you injected the medicine.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Many other medicines can affect your blood sugar, and some medicines can increase or decrease the effects of insulin. Some drugs can also cause you to have fewer symptoms of hypoglycemia, making it harder to tell when your blood sugar is low. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using. This includes prescription and over-the-counter medicines, vitamins, and herbal products.