How Do You Use Basal Insulin?

When the first long-lasting basal insulin analogs (insulin glargine [brand name Lantus] and insulin detemir [Levemir]) came out, they were supposed to last 24 hours. You injected once a day. That schedule clearly doesn’t work for everyone. Why is that, and what works for you?

First of all, what is “basal” insulin? “Basal” insulin is that background level of insulin you need 24 hours a day. It’s not for the food you eat; it’s for everything else insulin has to do in your body. As I wrote here, insulin keeps glucose stored in the liver, fat stored in fat cells, and promotes cell reproduction, along with several other functions.


People with Type 1 and many with Type 2 have very low or no basal insulin. Without basal insulin, your liver can pump out glucose all the time. Your sugars can go way up even if you don’t eat, like at night.

So the invention of a 24-hour basal insulin was a great advance. It brought people’s A1C levels way down, but it doesn’t always work as advertised. Dr. Richard Bernstein, author of Diabetes Solution, says “In my opinion, there is no 24-hour basal insulin.”

Larger insulin doses take longer to absorb. According to Dr. Bernstein, drug companies used larger-than-needed doses to make them last 24 hours. “The large basal doses needed to make ‘long-acting insulins’ last 24 hours,” he says, “[can cause] a number of undesirable consequences. These include hypoglycemic episodes [lows], weight gain, and possible [blood vessel] effects.”

At the proper doses, basal insulin will frequently not last 24 hours. A study in Diabetes Care found a window of low insulin levels when the daily dose has worn off and the next day’s dose hasn’t yet kicked in. The authors suggested twice daily dosing would provide better coverage.

Other researchers disagreed, finding that twice daily dosing “tended to increase total insulin dose [too much relative] to improvement in control.” These authors suggested a bolus of short-acting insulin to cover the down time between daily doses.

Changing the time of dose makes a difference too. “Morning administration tends to require higher dosing than evening administration,” the authors wrote.

Physicians Assistant John Walsh, PA, CDE, wrote on Diabetes Net that “probably at least a third of all users do not get a full 24 hours of action from [Lantus].” Basal insulins are not supposed to have “peaks,” but some people notice a peak of action about six hours after injection. Those people are less likely to have their dose last a full 24 hours.

Levemir seems to last a little shorter time, maybe 12–16 hours, so should more likely be split into two doses.

Again, smaller doses of either drug absorb faster and are more likely to cause hypos 4–6 hours after dosing and to stop working long before the 24 hours is up. People with Type 1 are more likely to be on small doses, so may need to split them. “Splitting the [dose] evens out dosing gaps and minimizes peaking. After splitting, most people find they have better readings,” Walsh writes.

Basal insulin testing
I asked people on diabetes message boards and chats how they handle their basal insulin. Most everyone agreed you have to find out for yourself — often with a doctor’s or diabetes educator’s help — what works best.

A poster on Diabetes Daily wrote, “I need much more basal insulin overnight, so I split my dose [taking more in the evening] to wake up with a good morning number and not go low before dinner.” He said it took “basal insulin testing” to figure out how much to take when.

Basal insulin testing is a big deal, since it involves fasting, frequent glucose checking, and careful record keeping. You are measuring how your body maintains glucose levels when there is no food in your system. If your glucose level goes down, it means too much basal insulin. If it goes up, you don’t have enough.

Because you’re fasting, you can’t test a whole day all at once. Any eating, abnormal amounts of exercise, or changes in your metformin schedule (if you’re taking it) will throw off the results.

An excellent article on basal testing can be read here.

Everyone is different
A participant on the social networking site Tu Diabetes told me, “Every physiology is different. Some get good results from a single injection. Others (like me) get better outcomes from splitting the dose in two.”

I even met a few people online who split their basal into three injections a day, although that sounds complicated and possibly dangerous to me.

An alternative to basal insulin is an insulin pump, which trickles out small amounts of fast-acting insulin all day, like a healthy pancreas does. You can add extra insulin to cover meals by pushing a few buttons. The upside is no injections. The downside is that pumps have more working parts to go wrong, cost more, and need more attention than injections do.

My questions for you are: Do you take basal insulin? How often do you take it? How is it working for you? Please let us know.




    Interesting. I started on a relatively low dose of Lantus and eased up over the years. I’m currently at 50 units and wondered if it might not be better to split that. I’ve seen discussions online where people were actually taking more Lantus than the pen would dispense in a single dose, and their concensus was better to space out the doses than take it all at once. As an aside, my cat is also a diabetic on Lantus, and her vet stressed the importance of a 12 hour dose schedule. Obviously feline physiology is different, but I think I’ll ask my Doc about splitting mine. I have very high glucose in the AM, but my A1c is fine. I’m thinking it just runs out overnight, causing a liver-induced spike.

  • Sherry

    I split my dose to take 12 hours apart, a short in the morning and a shot in the evening. I also take a shot of the fast acting insulin at meal time with a sliding scale amount. I am still having problems controlling my blood sugar levels.

  • KC

    Due to a change in insurance I had to switch from Lantus to Levemir back in September of 2014. I went from taking 45 units of Lantus to 56 Units of Levemir, but my numbers have been pretty poor since the switch. My endo and I have made the decision to go to a pump and avoid the long acting insulin types for basal covereage. I am now just waiting for the pump and the CGM system to arrive. I will be going on the Animis Vibe system which combines an Animis Pump with the Dexcom CGM. Hopefully this gets thing under better control. I have had T1 for 23 years and I currently have the worse control and as a result HbA1c numbers ever.

  • Kathleen

    I have used the Levemir pen for 7 years. I take about 20 units at night I started at 12. What really makes a difference in my AM readings is what I eat at night and what time and if I exercise. I am having trouble starting up my exercise again.

  • Anton

    I’ve had big issues with Lantus. I get a pronounced peak 4-6 hours after injection and after <20 hours it's all gone. Taking it twice a day just made things more random! After a lot of trial and error with different times for injection I've concluded that, for me, taking it once a day at 6 pm works the best! My blood sugar tends to rise during the evening so the peak actually becomes useful, or at least less disruptive, between 10-12 pm instead of giving me a low as it did before. I do still have the issue of Lantus not working 24 hours but I cover the gap with Humalog.

  • David Ramírez

    I’m on Lantus from about 3 years now, but my A1c have been not regular and proning to get higher in the last year, and this article may be showing how the basal insuline may not be enough to treat or get healthier and steadier levels. Tnx

  • dufus

    I have just started using Lantus injections. My problem is low, sometimes too low (77) readings in the am. I take a very low dose of 10 units in the morning, along with glimipiride 2 mg in am and again with supper. And my glucose reading 3 hrs after supper are too high!.(200+) After 3 mos., I have gained 10 lbs and my AIC did not change at all, even though I have cut down a lot on my carbs . Now my dr has switched my inuslin to NPH 2x daily.

  • Vasiliki Didaskalou

    I was fed up with my poor control. After 20 years. I refused to see the doctor diabetic nutritionist and decided to go about it alone as of last year. I started research Potassium to understand why my levels where so low and self educated myself on the endochrine system and took my own risk to eliminate carbs out of my diet and was eating just parsley for lunch and other things until I could figure it out. It really worked for me and I thought if my clinic gets it wrong on how much carbohydrate to eat what else is wrong … and to cut a long story short I have discovered a community of T1 who are doing LCHF and I finally feel “home”. I have a lot to learn that I cant work out on my own. I want to adjust my Levemir but dont know how to do this … and I want to get strict and be at 5% (even though in the last 3 months I went from 12% average to 7% on my own efforts). Now, using the experienced I want to get my efforts of 7% down to that 5%!!

  • Vasiliki Didaskalou

    I just can not find someone to lean on in working out the best protocol to adjust it … no one in the medical profession around me is even aware of LCHF and how it works let alone how to use that information to perfect insulin dosing and timing.

    • Hi Vasiliki, I’m not sure why your doctor can’t help you with this, but there are websites that write about low-carb, high-fat with insulin. One is called Diet Doctor and another is an English site called Low-Carb Diabetic.