Basal Insulin Switch Improves A1C in Type 1 and Type 2

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Basal Insulin Switch Improves A1C in Type 1 and Type 2

Switching from another basal (long-acting) insulin type to either insulin degludec (brand name Tresiba) or high-potency insulin glargine (Toujeo) led to improvements in long-term blood glucose control for people with both type 1 and type 2 diabetes, in a new study published in the Journal of Diabetes Investigation.

Basal insulin is essential for people with type 1 diabetes who don’t use an insulin pump, since it mimics the slow, steady release of insulin that happens in a normal pancreas. People with type 1 also need to take bolus doses of short-acting insulin at certain times during the day, especially before eating, to mimic the quick release of insulin from the pancreas in response to food. Many people with type 2 start taking basal insulin when oral medications can no longer adequately control blood glucose levels, and for some of them, basal insulin is enough to reduce glucose enough to reach their treatment goals.

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For the latest study, researchers were interested in comparing the effectiveness of insulin degludec and high-potency (300 U/ml) insulin glargine against other types of basal insulin that study participants switched from. They looked at changes in A1C (a measure of long-term glucose control), body-mass index (BMI, a measure of body weight that takes height into account), and insulin doses in 307 participants with type 1 and 294 participants with type 2 diabetes. All participants started out with an A1C level higher than 7.0%, meaning that there was room for improvement according to guidelines from the American Diabetes Association and other official organizations.

Doses of insulin were not standardized for this study, since insulin doses are almost always recommended on an individual basis that takes the person’s response to the insulin into account. In practice, this meant that doses of insulin glargine tended to be higher than those of insulin degludec in the study. There were other notable differences between participants who switched to insulin degludec versus insulin glargine, as well as differences between those with type 1 versus type 2, as noted in an article at Endocrinology Advisor. Participants who switched to insulin degludec were less likely to also take diabetes medications in the GLP-1 receptor agonist or SGLT2 inhibitor classes. The average age of participants with type 1 who switched to either insulin degludec or insulin glargine was 47, while the average age of participants with type 2 was 65 for insulin degludec and 64 for insulin glargine. Participants with type 1 were mostly women — 69.2% and 67.9% in the two insulin groups — while those with type 2 were mostly men — 58.5% and 56.1% in the two insulin groups.

In both insulin groups, A1C levels dropped significantly — an average drop of 0.3% for participants with type 1, and a drop of 0.5% for those with type 2 diabetes. For both insulin types and for people with type 1 or type 2, there was little to no change in the amount of basal or total insulin they took after switching. In people with type 1, BMI increased by an average of 0.11 in both insulin groups — while in people with type 2, BMI increased by an average of 0.15 for insulin degludec and decreased by an average of 0.09 for insulin glargine. Each of these BMI changes represented less than a 1% change.

The researchers noted that comparing insulin degludec with high-potency insulin glargine in this study is difficult, since people who previously took standard-potency insulin glargine (Lantus or Basaglar) were more likely to switch to high-potency insulin glargine than to insulin degludec. But the overall results show that despite some differences in the details, switching to either insulin degludec or high-potency insulin glargine led to improvements in blood glucose control for people with type 1 or type 2 diabetes, with a minimal change in BMI. These results are consistent, the researchers wrote, with what previous studies have shown regarding the effects of different types of basal insulin.

Want to learn more about insulin? Read “What Does Insulin Do?” “Insulin: What You Need to Know” and “Insulin Basics.”

Quinn Phillips

Quinn Phillips

Quinn Phillips on social media

A freelance health writer and editor based in Wisconsin, Phillips has a degree from Harvard University. He is a former Editorial Assistant for Diabetes Self-Management and has years of experience covering diabetes and related health conditions. Phillips writes on a variety of topics, but is especially interested in the intersection of health and public policy.

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