Basal Insulin Selection
Long, Longer, Longest: Individualizing Basal Insulin Selection

Released: September 26, 2023

Expiration: September 26, 2024

Steven V. Edelman
Steven V. Edelman, MD

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Key Takeaways
  • The ideal basal insulin should have low variability, have a duration of action of at least 24 hours, and work well for the patient.
  • CGM data are invaluable when adjusting or changing basal insulin.
  • If CGM is not available, consider paired postprandial and fasting morning blood glucose to determine if basal insulin needs to be changed or adjusted.

When I have patients with type 2 diabetes (T2D) who I think need a basal insulin to improve their control, I look for an insulin that is consistent with less variability (ie, no peaks or valleys), has at least a 24-hour duration of action, and acts as a good foundation should fast-acting insulin need to be added in the future.

In general, I think the second-generation basal insulins are significantly better than the older neutral protamine Hagedorn (NPH) and first-generation basal insulins, insulin detemir and insulin glargine U-100. But is there still a place for the older insulins regardless of financial considerations? Although I do not think there is any role for NPH insulin with its peaks, valleys, and lack of duration of action, there are patients who do well with insulin detemir and insulin glargine U-100. If things are working well and access to a first-generation basal insulin is easier, then I do not see any reason we would not continue using them. I think we have to assess each patient’s situation differently.

Switching Between Basal Insulins and Key Considerations Leading to Changing the Basal Insulin
When I look at a patient receiving basal insulin, I consider many factors to assess safety and efficacy. I think one of the most important tools I have is continuous glucose monitoring (CGM). CGM really tells me what is going on 24/7. A typical download covering a 1-month period allows me to review the patient’s readings and blood glucose trends and to determine if that patient needs to adjust the basal insulin, increase or decrease the dose, or switch to another basal insulin that may have flatter pharmacokinetic curve with a longer duration of action. Data from frequent home monitoring of blood glucose or CGM are needed to make these decisions.

Currently, any patient receiving basal insulin is eligible for CGM—even patients with T2D who are not receiving fast-acting insulin. CGM is the standard of care for patients with type 1 diabetes, and this was expanded to include patients with T2D receiving 3 or more injections per day. As of March 2023, both Medicare and the American Diabetes Association support the eligibility of patients with T2D receiving basal insulin for CGM.

I feel that most patients with T2D, no matter where they are in their natural history, could benefit from CGM. For example, it is amazing to see the behavior modification that a patient with prediabetes can achieve after seeing how their blood glucose varies depending on what they are eating, how much they are eating, the nutrient composition of what they are eating, and their exercise duration and severity. It can be a valuable tool, and I predict that someday CGM will be the standard of care for patients with T2D, whether you are adjusting insulin with it or not.

Insurance Coverage for the Newer Basal Insulins
Access is typically a major problem for many people and depends on their insurance company. If the option for your patients is either insulin glargine U-300 or insulin degludec, then it does not really matter. They are both very similar, and I would not fight that battle of one vs the other.

However, if neither of them is available, then as the healthcare professional, you may have to do a prior authorization and show evidence that the patient needs a flatter, longer-acting, and more consistent basal insulin. That data are most likely going to come from CGM. The second-best option would be a patient who tests his or her blood sugars more often. This is where paired testing at night may be useful, as the patient can test again in the morning and see if his or her blood glucose is much higher in the morning. If the high morning blood glucose is repeated for a couple of days, that indicates a need to increase the dose of the current basal insulin. If that leads to hypoglycemia, that is evidence that the patient needs a flatter basal insulin. That is just one example, but you will need to have some evidence to support the prior authorization.

Individualizing Basal Insulin
No matter which basal insulins your patients have access to—and I do believe that they will do much better with the second-generation basal insulin because of the flat profile and longer duration of action—you really need to make sure that once you initiate the dose, you titrate it appropriately. Occasional bedtime blood glucose also should be obtained so that you know you are not fighting off a high postprandial blood glucose and inappropriately increasing the basal dose. This can result in overbasalization, which is not uncommon. Although we do look at the fasting blood glucose quite a bit, some healthcare professionals forget to occasionally look at the bedtime blood glucose. If the bedtime blood glucose readings are elevated, you need to do whatever you can to get them to goal, and then you can truly test the dose of basal insulin your patient may need.

Your Thoughts?
In your practice, which factors do you consider most important when changing basal insulin? Answer the polling question and leave a comment to join the discussion.

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In your practice, which factors do you consider most important when selecting or changing basal insulin?

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