Hesperian Health Guides

Injectable Medicine for Diabetes

Diabetes: Medicines


Insulin is a hormone produced in the pancreas that helps the body process sugar in foods. It is necessary for life, and if the body cannot produce it, a chemical form of insulin must be used instead. All people with Type 1 diabetes will need to take insulin for life. People with Type 2 diabetes may also need to use insulin if their own bodies stop producing it. When this happens, oral medicines such as metformin or sulfonylureas are no longer sufficient and insulin may be the only way to manage blood sugar levels.

Insulin must be injected. It may come in a vial, and you can use a syringe to prepare the correct dose. It can also come in a device that looks like a pen which measures the correct dose and is easier to use.

There are 3 types of insulin:

  • Short-acting: The most common type of short-acting insulin is called “regular” insulin. Lispro and aspart are also short-acting. This type of insulin is used before meals.
  • Long-acting: NPH is the most common long-acting insulin. Glargine and determir are also long-acting. This type of insulin is used 1 or 2 times a day.
  • Mixed dose or pre-mixed: The most common combination of long-acting and short-acting insulins is NPH /regular 70/30, which is used 2 times a day. Another common mixed-dose insulin is NPH /regular 50/50.
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Insulin can make the blood sugar go too low too quickly (see Diabetic Emergencies).

Weight gain can be partially prevented by eating well and staying active after starting insulin.


The risk with insulin is that it will make the blood sugar go too low, which can become a medical emergency. This is more likely to occur if someone skips a meal, has had a lot of exercise, or takes too much insulin by mistake.

It is important that the person using insulin understands how to use it safely and can recognize the danger signs of low blood sugar. If not, she must have adequate help at home. A person with limited vision will also need extra help to make sure she takes the right dose.

If the person uses both long-acting and short-acting insulin, it is very important that she understands the difference between them and uses them correctly.

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Insulin should be kept in a cool place, away from extreme hot or cold. It can be stored in a refrigerator but never freeze insulin.

For anyone taking diabetes medicines, testing a drop of blood to measure blood sugar can show how well the medicine, or a specific dose of the medicine, is working. Usually, a person starts with a low dose and then the dose is increased little by little. So more tests than usual are done when starting a new medicine to help find the dose that works best.

People who have Type 1 diabetes need insulin every day to be healthy. Long-acting insulin is needed to stabilize the person overnight and throughout the day and the person learns how to adjust doses of short-acting insulin depending on meals and when they are active physically. Experienced health workers will help the person and her family determine the types of insulin and the dose that will work best.

People with Type 2 diabetes often start taking insulin with a once a day injection of long-acting insulin, either alone or in addition to oral medicines like metformin or sulfonylureas.

First doses of long-acting insulin should be low dose, such as 10 units. If you start with a single injection of NPH , it should be given at night. But because NPH only lasts about 12 hours, many people take it 2 times a day to avoid swings in blood sugar.

Your health worker may have you increase the amount of long-acting insulin very slowly over time until the blood sugars are no longer high. Once the blood sugar is in a good range, you continue to take the same dose every day. It can take many weeks to get to the correct dose.

Blood sugars may be at a good level in the morning, but high after meals. If this happens, the person may also need a short-acting insulin, such as regular insulin, given before meals. Short-acting insulin should also be started at a low dose, around 4 units. It can often be started once a day before the largest meal, but for some people it will need to be used before every meal. Regular insulin should be taken 30 minutes before eating. Frequently measuring your blood sugar at first will help your health worker adjust the dose of short-acting insulin you will need.

Mixed dose insulin is another alternative for people who need more than just long-acting insulin. For example, NPH /Regular 70/30 is given 2 times a day, 30 minutes before breakfast and 30 minutes before dinner.

Signs of taking too much

The danger signs of low blood sugar include difficulty walking, feeling weak, difficulty seeing, confusion, loss of consciousness or seizures. If the person is conscious, they need something sweet quickly and then a full meal as soon as possible. If the person is unconscious, place a pinch of sugar or honey under his tongue and keep giving small amounts until he wakes up and can take more himself.

This page was updated:05 Jan 2024