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.