By Martha Funnell, MS, RN, CDE

Q How does the body use insulin?

A Insulins today are very similar to the natural insulin your body makes. Diabetes means your body has a problem making insulin, using it effectively or both. Without insulin, the glucose stays in the blood and your glucose level gets higher and higher. You need insulin to move glucose (sugar) from your blood into the cells of your body where it is used for energy. Before you got diabetes, your body made enough insulin to keep your blood glucose level close to normal all the time. No matter what you ate or how much physical activity you did, your blood glucose usually stayed between 70 and 115 mg/dL. To keep your blood glucose level in this range, your pancreas pumped out insulin at two different rates. The first was a slow, steady stream of insulin that your pancreas made just about all of the time. This is called the basal, or background, level of insulin. In addition, your pancreas also pumped out a burst of insulin when you ate. This is called bolus, or mealtime, insulin, and it helped your body handle the surge of glucose from your food.

Q What is basal insulin?

A Your body needs insulin all the time, not just when you eat. Basal insulins keep your blood glucose on target between meals and while you are sleeping. They do not have much effect on your after-meal blood glucose levels. If your blood glucose level is close to normal in the morning, it is easier to stay on target the rest of the day. If your blood glucose level is high when you wake up, you may need a basal insulin. 

Q How do the different types of basal insulin work?

A Many people with type 2 diabetes take basal insulin along with their diabetes pills or in combination with a bolus type of insulin. There are three main basal insulins. While all three of these give you a basal level of insulin, they work in slightly different ways.

NPH: THE FIRST BASAL INSULIN

It lasts for 12-16 hours and reaches its maximum effect about eight hours after you take it. Most people need to take NPH insulin twice a day. NPH insulin may be taken alone or as a premixed form of NPH + bolus insulin, such as 70/30. Mixes made with analog insulins (Humalog 75/25, Humalog 50/50 and NovoLog 70/30) are on the market, as well. Premixed insulins give you both the basal and bolus insulin in one dose. The names of bolus insulins are lispro (Humalog), aspart (NovoLog) and glulisine (Apidra). You can draw both types of insulin into one syringe so you only need to take one shot.

GLARGINE (LANTUS) & DETEMIR (LEVEMIR): A NEW CLASS OF BASAL INSULINS

Both last for about 24 hours and do not have a peak. They are taken once a day (usually at bedtime) or twice a day (once in the morning, once at night). Glargine and detemir only cover your basal insulin needs. Most people also need to take pills or a bolus insulin to keep their glucose levels on target after meals. 

Q Which basal insulin is best for me?

A The best insulin is the one that works best for you—which means it is the easiest for you to use, causes the fewest problems and keeps your blood glucose on target. All insulins work to lower your blood glucose level. Just like everything else, there are pros and cons to each of the basal insulins.

NPH INSULIN

NPH insulin has a peak, which means you need to match the times you eat with the peak to avoid a low blood glucose reaction. Most people take two injections of NPH every day. 

GLARGINE OR DETEMIR INSULIN

If you use glargine or detemir, you may be able to take just one shot per day, but some people need two. Regardless of which insulin you choose to use, you are likely to start with a small dose and gradually increase the amount you take. Low blood glucose reactions are less common with these than with NPH or premixed insulins. You can use either an insulin pen or a syringe to take these insulins. Basal insulins work slowly to help keep your blood glucose levels steady. As the saying goes, slow and steady wins the race—and can help you to better manage your diabetes.

6 ways to get the most from your basal

1. Take your basal insulin at the same time every day.
2. Don't mix glargine and detemir in the same syringe used for other insulins.
3. Check your blood glucose level before bed and when you get up in the morning. Your blood glucose levels should be about the same. If they are not, you may need to change your dose.
4. You may notice some weight gain when you start taking insulin. Some people find that they are less likely to gain weight with detemir.
5. Your dose of basal insulin may need to change often at first. For most people, this is about every five-to-seven days. Be sure to ask your health care provider if and when you need to change your dose. Do not wait until your next appointment to talk to your provider if your blood glucose levels are not on target.
6. It may be tempting to skip a dose of your basal insulin when your blood glucose is on target. Remember, your basal insulin lasts for a long time. If you skip a dose, you will not have the insulin you need for the rest of the day or night.