Determining the Best Basal Insulin Dose for People With Type 2
If you’re like a lot of people with type 2 diabetes, you may need to add insulin injections to your daily routine. This happens when the disease has progressed and your other medications can no longer keep your blood glucose levels where you and your health care team want them to be.
Many people start insulin therapy with a once-daily injection of a long-acting insulin. This is called basal (or background) insulin. At the right dose, it will keep your blood glucose levels consistently in range overnight and between meals. You and your provider will work together to find the dose you need. This process is called titration. You’ll likely begin low and go slow.
“If you start at a low dose, it’s not going to be enough to get your blood glucose where it needs to be, but it reduces the risk of hypoglycemia, or low blood glucose, as we gradually work toward the amount you need to take,” says endocrinologist Matthew Freeby, MD, director of the Gonda Diabetes Center at the David Geffen School of Medicine at the University of California–Los Angeles.
How much basal insulin will you need at first? “When you start, it’s a guess, though one that’s based on certain factors,” says Carla Cox, PhD, RD, CDE, FAADE, a spokesperson for the American Association of Diabetes Educators. Two of the factors that your provider may use to determine your starting dose will be your fasting blood glucose level and how much you weigh.
A typical formula, according to the American Diabetes Association’s Standards of Medical Care in Diabetes, is 0.1 to 0.2 units of insulin per day per kilogram of body weight. For example, if you weigh 200 pounds, or about 91 kilograms, your health care provider may have you start with a dose somewhere between 9 and 18 units.
Your doctor may instruct you to increase your long-acting insulin by a unit or two every one to three days, though some providers recommend less-frequent dose changes. However often you adjust your dose, you’ll do so until your fasting blood glucose level is within your target range, says Chris Memering, BSN, RN, CDE, FAADE, a certified diabetes educator with CarolinaEast Health System in New Bern, North Carolina. “It may take a week. It may take longer,” says Memering. “It depends on where you start your dose level and how you make adjustments.”
Freeby recommends that you stay in frequent contact with your provider at this early stage. “When you’re starting on insulin, it’s all about the feedback on what’s happening throughout the day in terms of both high blood glucose levels as well as lows,” he says. For instance, if you’re dealing with hypoglycemia, your doctor may want to reduce your insulin dose faster than your algorithm dictates. Call your doctor’s office, talk to your educator, or send an e-mail with whatever questions and concerns you have.
Endocrinologist David Ahn, MD, program director of the Mary and Dick Allen Diabetes Center at Hoag Hospital in Newport Beach, California, says that the algorithms that providers use to get you to the proper dose are often quite simple. They consist of a few basic instructions, and Ahn says most of his patients find them easy to follow.
Let’s say you’re a 50-year-old man who weighs 250 pounds and was diagnosed with type 2 diabetes 10 years ago. A typical scenario: Your doctor starts you on 10 units of long-acting insulin with a fasting blood glucose goal of between 100 and 150 mg/dl. When you check your blood glucose the next morning, it’s above 150 mg/dl. The plan calls for you to add 2 units to your dose. You’ll keep checking your blood glucose every morning and raising your dose of insulin by an additional 2 units each day until your fasting blood glucose is in range. On the other hand, if your blood glucose drops below 100 mg/dl when you start, you’ll reduce your dose by 2 units each day until it’s in range. The goal: a dose that will remain steady until circumstances require a change.
Such adjustments put some of the decision-making in your hands. That may sound scary, but most people with type 2 diabetes do quite well. In fact, you may do better on your own than you would if your doctor decided everything. A study published in 2019 found that people who received titration instructions from their doctors and calculated their own dose adjustments did a better job of reducing their A1C than those whose doctors adjusted their dose during office visits. And those figuring their own doses were no more likely to have episodes of hypoglycemia, and they felt more at ease emotionally.
Still, says Ahn, some people struggle. About a third of his patients make mistakes because they’re uncomfortable with the math required to calculate their adjustments or they misinterpret the instructions on how to make those adjustments.
That’s where emerging tech may help. In recent years, the Food and Drug Administration (FDA) has approved a few prescription-only smartphone apps—iSage RX and My Dose Coach, among them—that calculate your basal insulin dose for you. Your provider enters your titration algorithm and gives you an access code. Once you install the app and sign in, it prompts you to log your fasting blood glucose every day. The app uses that info to calculate your dose. Easy enough, right?
Ahn, who specializes in diabetes technology, says that the steps required to use the apps can be burdensome for both providers and patients. “Your provider has to prescribe the app, you have to download the app and make sure that it is configured to your personal settings,” says Ahn. “And 90 percent of the time, all of that will be more complicated than just writing down your specific algorithm on a piece of paper.”
Ahn hopes that the developers will make their apps easier to use. For now, though, he doesn’t consider them an essential tool. Very few of his patients use them. Those who do tend to be particularly interested in technology.
Time Marches On
Once your basal insulin dose has been optimized, you won’t have to adjust it on a daily basis. Over time, though, your needs may change. Freeby teaches his patients to look for trends in their blood glucose levels and to make adjustments accordingly, with input from him if they need it.
“For example,” he says, “if you have begun to exercise and have started to lose weight, that may be an opportunity to reduce your insulin dose.”
On the other hand, as your diabetes progresses, you may have to go to a higher dose or add rapid-acting (bolus) insulin to your routine. Brief health changes, such as catching the flu, can temporarily change your basal insulin needs. “If you get sick,” says Freeby, “we might boost your insulin by 10 to 20 percent to compensate for the rise in blood glucose that occurs due to stress hormones, which trigger the liver to produce more glucose.”
Other circumstances that may call for temporary adjustments to your basal insulin, which your provider can help you manage, include stress; pre-menstruation; ongoing sleep problems, such as insomnia or sleep apnea; and pregnancy.
“These and other factors will increase or decrease your insulin requirements, so it’s crucial to understand what those factors are and what may happen when they occur,” Freeby says. “With insulin therapy, education is vitally important.”