Continuous glucose monitoring systems have become easier to use Image by Andrey Popov
Continuous glucose monitoring systems have become easier to use. Image by Andrey Popov

Shifts in insulin use

Physicians' management of patients who take insulin for diabetes has been influenced by changes in pricing and access to technology.

One out of every eight American adults diagnosed with type 1 or type 2 diabetes will start taking insulin within a year, according to federal data from 2021. Physicians' management of these patients continues to shift, influenced by changes in pricing and improved access to continuous glucose monitoring (CGM) systems and other technology that can improve blood glucose control.

Recent federal legislation, as well as caps set by insulin manufacturers and some state laws, has provided price relief for patients, depending upon their insurance coverage. Meanwhile, CGM systems have become easier for patients to use, and both price and insurance coverage have improved, making them more accessible to patients with type 2 diabetes, said Thomas Martens, MD, FACP, an internal medicine physician and medical director at the International Diabetes Center at HealthPartners Institute in Bloomington, Minn.

Other insulin-related developments include a move by federal officials last year to broaden Medicare coverage of CGM systems (patients previously didn't qualify unless they already were using an insulin pump or required multiple daily insulin injections). Emerging medication issues include the expanding use of glucagon-like peptide-1 (GLP-1) receptor agonists and sodium-glucose cotransporter-2 (SGLT-2) inhibitors for diabetes, as they can spur weight loss, which may alter a patient's insulin needs over time. Also last year, Novo Nordisk applied to FDA officials for approval of the first once-weekly insulin icodec; the manufacturer reported that it anticipates a decision this April.

Insulin pricing changes

The Inflation Reduction Act, which included a $35 monthly cap on out-of-pocket spending for each insulin product, kicked in on Jan. 1, 2023, for Medicare patients enrolled in Part D and on July 1, 2023, for those enrolled in Part B. As of 2019, patients covered by private insurance or Medicare paid about $63 per 30-day supply and uninsured individuals roughly double that amount, according to an issue brief by federal officials published on Jan. 24, 2023.

In short order, starting in early March 2023, three insulin manufacturers announced a $35 cap for patients covered by commercial insurance for some insulin products. The start date varied depending on the manufacturer and the product, with all manufacturers offering some type of pharmaceutical assistance programs for uninsured patients. In addition, roughly half of the states in the U.S. have implemented various price caps on a monthly insulin supply for individuals covered by state-regulated commercial health insurance plans, according to the American Diabetes Association.

The price reductions and caps make insulin analogs more affordable, giving physicians the option to switch patients from older human insulins to those drugs, said Lillian F. Lien, MD, FACP, director of the division of endocrinology, metabolism, and diabetes at the University of Mississippi Medical Center in Jackson. "To be quite frank, this is something that we have waited years for," she said.

Sometimes the older human insulins will remain an appropriate option for subgroups of patients, such as those on steroids, given that their duration of action may mimic the effects of certain steroid regimens, Dr. Lien said. But the insulin analogs provide more flexibility in terms of timing of dose administration for the majority of patients, she said.

Physicians also should consider approaching certain patients only on oral medications about changing to a regimen including an insulin analog now that it's more affordable, particularly if the patient's HbA1c level has consistently been 10% or higher, she said.

Still, patients may continue to fall through the cracks, said Mariana Socal, MD, PhD, an associate scientist in the department of health policy and management at Johns Hopkins Bloomberg School of Public Health in Baltimore, who coauthored an opinion piece published online Sept. 5, 2023, in Annals of Internal Medicine looking at insulin pricing changes.

For instance, although patients without insurance can apply for help through manufacturers' patient assistance programs, there's no guarantee that they will be accepted or that their access to free or reduced-rate insulin will continue moving forward, Dr. Socal said.

"Because they depend upon the manufacturers," she said. "They can rescind the program at any time. They can change the enrollment criteria at any time."

Increasing technology access

While the traditional fingerstick monitoring can be effective, Dr. Martens said, "the issue in the real world, and especially in primary care settings, is that it tends to be underused by patients because it's a burden to prick your finger." About five years ago, FDA officials began to approve CGM systems that no longer relied upon fingersticks for calibration, said Dr. Martens, who reports serving as a research investigator, speaker, and/or consultant/advisory board member for Abbott Diabetes Care, DexCom, Insulet, Eli Lilly, Medtronic, Novo Nordisk, Sanofi, and Tandem.

"CGM is much, much easier to use than it was in the past," he said. "The data is there whenever you want to look at it—it's on your smartphone. You can see your glucose any time of day or night."

The price also has been declining, Dr. Martens said, as the manufacturers vie to capture a share of the large population of patients using insulin to treat their type 2 diabetes. At this point, roughly one in five patients with type 2 diabetes getting primary care through HealthPartners' health system are using the technology, he said, noting the figure is based on an informal survey.

Primary care physicians should discuss these systems with their patients, particularly those who use background and mealtime insulin, given the complexity involved, as well as those who may be more vulnerable to undetected hypoglycemic episodes while asleep, Dr. Martens said. "There's this invisible hypoglycemia that if you're using fingerstick blood glucose monitoring you may not even be aware of," he said, "but we know that it makes your outcomes worse."

Dr. Martens was the lead author on a study comparing the effectiveness of a CGM system versus fingerstick monitoring in a randomized trial of 175 patients with type 2 diabetes using basal insulin. The group using the CGM system had fewer hypoglycemic episodes and spent an average of 3.8 hours more each day within the optimal blood glucose range, according to the findings, published June 8, 2021, in JAMA. In addition, the HbA1c level, which declined in both groups, was 0.4% lower in the CGM group compared with the fingerstick group.

The relative effectiveness of the two approaches still must be studied outside the research setting, Dr. Martens said. "What we know is in the real world, the BGM [blood glucose monitoring] users just don't do as well as they do in research studies," he said, noting that patients are less likely to regularly collect their readings in the real world than in closely supervised research settings.

More insurers, including Medicare, have liberalized the coverage of CGM systems in the wake of the 2021 study and other recent data, Dr. Martens said. Starting last year, CMS began covering the systems for all Medicare patients with diabetes who are treated with insulin as well as those who struggle with hypoglycemia and meet related criteria. For instance, per the CMS criteria, that includes patients who have had two or more level 2 hypoglycemic events (glucose level <54 mg/dL) that persist despite multiple modifications to the medication or diabetes treatment plan.

At this point, most patients with type 1 diabetes who use a hybrid closed-loop system, which pairs an insulin pump with a CGM system, will be managed by an endocrinologist, as those practices have clinician educators, relationships with the technology companies, and other infrastructure to provide support, said Irl B. Hirsch, MD, MACP, an endocrinologist and professor of medicine in the division of metabolism, endocrinology, and nutrition at the University of Washington School of Medicine in Seattle.

But for patients with type 1 or type 2 diabetes who require multiple insulin injections and use a CGM system without an insulin pump, primary care physicians can play a notable role by regularly reviewing the ambulatory glucose profile patterns, as well as the time-in-range metrics, with the patient on a computer screen or a printout, rather than just briefly looking at the smartphone's data, said Dr. Hirsch, who reports serving as a consultant for Abbott Diabetes Care and receiving research grants from Dexcom and Tandem.

That closer view will enable the physician to explain patterns, such as a tendency to develop hypoglycemia overnight after too much basal insulin, or in the late afternoon following exercise, indicating that patients weren't dosing correctly at lunch, he said. He noted that this type of detailed review might be difficult for primary care physicians to manage in an already packed visit, "but it would be very, very helpful [for patients] to do that."

Emerging complexities

Several physicians highlighted the potential for newer classes of medications to complicate insulin dosing, since they drive weight loss along with treating type 2 diabetes. Dr. Hirsch reported that some of his patients with type 2 diabetes no longer require as much insulin after starting a GLP-1 receptor agonist. More than a handful of his patients have lost so much weight, sometimes as much as 60 pounds, that they don't require any, he said.

If a patient with type 2 diabetes is on insulin and a GLP-1 receptor agonist or a SGLT-2 inhibitor, primary care physicians should monitor them more closely and warn patients to more frequently check their blood glucose levels, said David O'Dell, MD, MACP, LeeRoy Meyer Professor in the division of general internal medicine at the University of Nebraska Medical Center in Omaha and physician editorial advisor for ACP Diabetes Monthly. "As their weight loss happens, they need to be aware of where their sugars are going and that they may very well need less insulin," he said. "And we don't want them to become hypoglycemic."

Another medication potentially on the horizon is icodec, a once-weekly basal insulin. To date, it's been mostly studied in patients with type 2 diabetes in a series of randomized ONWARDS trials. The ONWARDS 6 trial, published Nov. 4, 2023, in The Lancet, is believed to be the first randomized phase 3 study to compare the safety and efficacy of a once-weekly basal injection of icodec to a once-daily basal injection of insulin degludec in adults with type 1 diabetes. Researchers found that the weekly icodec was similarly effective to degludec in managing the disease.

Other research, looking at open-source automated insulin delivery (AID) systems in a total of 97 children and adults with type 1 diabetes, found some benefits. Such systems are sometimes dubbed "do-it-yourself" because they pair open-source insulin-delivery algorithms with compatible pumps and sensors. At 24 weeks, patients using an open-source AID system had increased the time they spent in the target glucose range from 61.2% to 71.2% versus a decrease from 57.7% to 54.5% in the control group, which used a sensor-augmented insulin pump. The findings were published Sept. 8, 2022, in the New England Journal of Medicine.

More than 10,000 individuals worldwide are using open-source systems, and their uptake continues, according to an international consensus statement and guidance for clinicians published in The Lancet Diabetes & Endocrinology in January 2022. The goal of the consensus statement was to review the existing evidence on open-source AID systems, including more granular detail about how they work, and assuage some nervousness among clinicians, said Rayhan Lal, MD, an endocrinologist and coauthor on the consensus statement as well as an assistant professor of medicine and pediatrics at Stanford University in Stanford, Calif.

"I think a big part of it was just telling [clinicians] that you don't have to turn your back on people because they decide that they want to use something that doesn't have a regulatory clearance," said Dr. Lal, who presents both commercial and open-source options to his patients. "This is not something foreign to any of us in medicine. People use drugs off label all of the time, and they don't give that a second thought." He reports receiving research grants/contracts and honoraria and/or serving as a consultant for Abbott Diabetes, Adaptyx, Biolinq, Capillary, Deep Valley Labs, Gluroo, Insulet, Eli Lilly, Medtronic, Physiologic, Portal, Provention Bio, Tandem, and Tidepool.

Amid reductions in the cost of insulin and improved access to technology, Dr. Lien remains hopeful that it will become easier for primary care physicians to care for patients with diabetes.

"Of course, if you're taking care of somebody who is on lots of insulin and you have no data and they can't afford their insulin, this is a challenging situation," she said. "Whereas as we transition, I hope, to a world where that same patient has access to CGM and access to insulin, then I'd say that's a real opportunity to help that person manage risk factors and potentially decrease their risk for so many terrible complications."