Best Bedtime Insulin for Gestational Diabetes, the Guide and Recommendations

Posted April 9, 2021 by Michael Chamberlain - See Editorial Guidelines

Being pregnant and managing diabetes brings about many lifestyle challenges. However, one thing that can make life easier is to find the best bedtime insulin for gestational diabetes.

In this article, we will explore the differences, comparisons, benefits, risks and offer our recommendation.

Let’s start with a quick reference answer before we head into more details.

Bedtime Insulin for Gestational Diabetes? Long-acting (basal) insulin such as glargine and detemir are the most suitable bedtime insulin for gestational diabetes. They work for 24 hours consistently with no peak concentrations, helping to decrease nocturnal hypoglycemia when sleeping. NPH insulin can also be used, but the performance is variable.

That’s the quick answer, but there are many variables here, so let’s get into some of the details that might affect your own personal use. Starting with the most effective.

For more information read our guide on living with diabetes.

Most effective bedtime insulin for gestational diabetes

Best Bedtime Insulin for Gestational Diabetes

Simply put, long-acting basal insulin is what is often recommended as the effective bed-time insulin for gestational diabetes, with some exceptions to intermediate insulin, such as NPH.

Long-acting insulins are also called basal or background insulins.

They keep working in the background to keep your blood sugar under control throughout your daily routine. And as the word suggests, they are “long-acting,” meaning they’ll have a consistent course of action lasting up-to 24 hours.

However, these types of long-acting insulin take the longest amount of time to start working. They can take up to 4 hours to get into your bloodstream.

So, timing your dose closer to bedtime is crucial to ensure it works while you’re sleeping. 

Besides this, some intermediate-acting insulin-like NPH that works for 10-12 hours is also recommended. In fact, NPH has previously been classed as the only “safe bedtime insulin for gestational diabetes” before the introduction of long-acting insulins.

How to check if your bedtime insulin is safe

In general, the time you take your long-acting insulin is flexible. The most important part is to take it at the same time every day, whether at night or in the morning.

However, the difference for gestational diabetes is that not all long-acting insulin should be used as bedtime insulin.

According to the FDA, only insulin that falls into the pregnancy safety category A and B is the most suitable for gestational diabetes.

Category A represents adequate, well-controlled studies in pregnant women and has not shown an increased risk of fetal abnormalities.

Category B states that animal reproduction studies did not demonstrate a risk to the fetus, yet there have not been enough studies on pregnant women.

The ones that fall into category C are considered safe only if the potential benefit justifies the potential risk to the fetus.

Using any other insulin that falls between pregnancy categories such as D and X either has no animal studies, poses risks to the fetus – including abnormalities, or causes other side effects to the mother, and can even result in a pregnancy loss.

This table helps summarize the main differences based on the pregnancy category.

Pregnancy Safety CategoryTests & StudiesRisk to Fetus and Mother
Category AControlled and adequate Study dataNo Increase in abnormalities
Category BInadequate study data but no known riskNo known increase in abnormalities
Category CInsufficient or no study dataUsed where benefits may outweigh risks to the fetus
Category D, XNot adequately testedPoses risk to both fetus and mother
pregnancy safety category overview for tests and risks

Suitable low-risk bedtime insulins for gestational diabetes

For the following types of bedtime insulin for gestational diabetes, the FDA has received sufficient human data allowing these to be considered low risk in pregnancy.

1. NPH (Humulin N, Novolin N)

NPH was initially considered as the only safe insulin for gestational diabetes, especially for bedtime.

Before the introduction of long-acting insulin, NPH was – in general – the most effective bedtime insulin for any diabetes patient.

Specifically for gestational diabetes, it falls into pregnancy safety category B, which is considered highly safe.

This insulin is identical to human insulin and is in a suspension. Its onset of action is 1–2 hours, with an average peak of 4 hours (range: 4–8 hours). The duration of action is around 12 hours. Therefore, NPH insulin is not long-acting but intermediate-acting. 

The reason why this is highly suggested as bedtime insulin for gestational diabetes even now is for its safety which has shown positive effects over a long history, and because it’s known to pose no risk to the fetus.

2. Glargine

Introduced in 2001, insulin glargine (Lantus) is a long-acting insulin analog with greater stability and duration of action than regular human insulin.

Insulin glargine starts to work several hours after injection and keeps working evenly for 24 hours.

It more closely mimics normal physiologic basal insulin concentrations than NPH. But they fall into pregnancy safety category C, so extra caution is needed before taking this as bedtime insulin.

Glargine is also associated with a 6- and 8- fold increase in binding to IGF receptor and mitogenic potency respectively when compared to regular human insulin.

3. Detemir 

Introduced in 2005, it is the first and only basal insulin analog that falls into pregnancy safety category B.

This means that detemir does not pose a higher risk or harm for the unborn when used in pregnant women with diabetes.

This works similar to glargine once injected. It has a long duration of action, up to 24 hours, making it suitable for bedtime insulin for gestational diabetes.

Best Bedtime Insulin for Gestational Diabetes, NPH, Glargine, or Detemir?

The key to effective bedtime insulin is that it should minimize the risk for nocturnal hypoglycemia. So, in that case, glargine or detemir stand out to be the best bedtime insulin for gestational diabetes.

Besides this, the state of action of NPH (intermediate-acting insulin) is highly variable. This variability causes difficulties with glucose control and leads to episodes of nocturnal hypoglycemia.

So, the main purpose of taking bedtime insulin to minimize or avoid nocturnal hypoglycemia is lost. 

One study also states that bedtime glargine supports less nocturnal hypoglycemia and better post-dinner glucose control compared to bedtime NPH insulin – especially with type 2 diabetes.

Similarly, in clinical studies, detemir also demonstrated a lower risk of nocturnal hypoglycemia and less weight gain than NPH, especially in type 1 diabetes. 

So, it appears that glargine or detemir are the most beneficial bedtime insulin for gestational diabetes.

And for a more concrete view, here are some benefits of those two options.

Benefits of glargine and detemir as bedtime insulin for gestational diabetes

  1. Very long elimination half-life (24 h) and avoids a peak in insulin concentrations. This helps maintain consistent blood sugar control throughout the night, decreasing the incidence of nocturnal hypoglycemia for gestational diabetes.
  2. These insulins offer tight glycemic control even at night because of their effect that lasts for 24 hours. And this tight glycemic control, especially during gestation, decreases the risk of maternal hypoglycemia and other fetal complications. 


If you are looking for the recommended option, then our advice is to enroll with us here and speak to us about detemir as an option.

Detemir falls into pregnancy safety category B that is extremely safe, whereas glargine falls into category C, which is considered cautious. This, of course, is also highly influenced by your type of diabetes and personal circumstances.

As we always recommend though, any decisions regarding your condition and treatment should only be made in conjunction with your doctor’s advice and consent.

More help for gestational diabetes patients

You can potentially get extensive help for your diabetes medications, including NPH, glargine, and detemir.

If you’re having trouble affording any of your medications, enroll with us and see if you qualify to pay only $50 a month for each of your medications.