Baltimore, MD—Over a 5-year study period ending in 2020, the use of insulin analogues and insulin glargine predominated, while the use of insulin pens and newer insulins also increased, according to a cross-sectional study of 27.9 million ambulatory insulin-treatment visits.

The report in JAMA Network Open points out that, although rising costs have drawn a lot of scrutiny, recent trends in insulin use in the United States have largely remained unknown.

That’s why Johns Hopkins University School of Medicine–led researchers sought to analyze data from a nationally representative audit of ambulatory care. Focusing on nearly 27.9 million insulin-treatment visits between 2016 and 2020, they found that analogue insulin was involved in more than 80% of all treatment visits, and among the insulin molecules, insulin glargine accounted for approximately half of treatment visits during the study period.

“In addition, the use of older insulins decreased, and the use of newer insulins steadily increased between 2016 and 2020,” the authors write. “Interestingly, the total treatment visits for insulin was at its lowest level in 2020.”

Among all patient encounters that indicated the use of insulin in 2020, 43.9% were among those aged 60 to 74 years; 52.4% were among men; 58.4% were among white patients; 17.9% were among black patients; and 15.5% were among Hispanic patients.

Insulin glargine was the most frequently used insulin from 2016 to 2020, involved in about half of treatment visits, with long-acting insulin accounting for approximately two-thirds of treatment visits during the time period.

In fact, treatment visits for insulin pens increased from 36.1% in 2016 (2.2 of 6.0 million visits; 95% CI, 1.7-2.7 million) to 58.7% in 2020 (2.9 million visits; 95% CI, 2.3-3.5 million). Use of insulin vials/syringes declined meanwhile.

The authors also write that analogue insulin use predominated and accounted for more than 80% of total treatment visits across all years. Still, newer insulins were increasingly used, from 18.1% of total treatment visits in 2016 (1.1 million visits; 95% CI, 0.8-1.4 million) to 40.9% in 2020 (2.0 million visits; 95% CI, 1.5-2.5 million).

The use of biosimilar insulin, which was first approved in 2015, increased from 2.6% in 2017 (0.1 of 5.3 million visits; 95% CI, 0.04-0.2 million) to 8.2% in 2020 (0.4 million visits; 95% CI, 0.2-0.6 million) of total insulin-treatment visits, according to the report.

The researchers say that their results provide updated data characterizing insulin trends and also offer greater detail regarding the use of different molecules and types of insulin, including delivery devices.

One key finding was that biosimilar insulin use increased by more than 200% from 2017 to 2020. The first biosimilar insulin to be approved in the U.S. was insulin glargine (Basaglar) in 2015.

Another finding was that analogue insulin accounted for most treatment visits throughout the study period. “These findings are consistent with older studies using privately insured payer cohorts and reports from resource-limited countries,” note the authors. “To our knowledge, our study is the first to document a continued predominance of analog insulin use in the United States using a multi-payer database and using the most up-to-date data available through the end of 2020.”

Researchers suggest that the continued predominance of insulin glargine, as opposed to newer insulins, “may be due to several factors, including clinical inertia, which has been commonly described in the treatment of patients with type 2 diabetes. In addition, expert guidelines note that analog basal insulins, including insulin glargine, are associated with less hypoglycemia compared with NPH (isophane) human insulin. However, they also highlight that insulin glargine U300 and insulin degludec may be associated with less hypoglycemia compared with insulin glargine U100 or insulin detemir.”

They pointed to the 2020 American Association of Clinical Endocrinologists and the American College of Endocrinology Consensus Statement, which advised that human insulins cost less than analogue insulins and can be a more affordable option. “Our study found that analog insulins accounted for most insulin treatment visits over recent years, implying that less costly options are not being used as frequently,” the authors add.

The COVID-19 pandemic likely explained a reduction in insulin use in 2020, the study states. The study relied on physician encounter forms and focused on adults with type 2 diabetes. The authors report that the total number of insulin-treatment visits declined from a peak of 6.0 million visits in 2016 to a low of 4.9 million visits in 2020, representing an 18% drop.

“To our knowledge, our study is the first to comprehensively report patterns of insulin use in the United States during the pandemic,” the authors point out. “Furthermore, insulin affordability and accessibility have been critically important to address, both prior to and during the pandemic. Federal and state legislations to limit insulin copay costs have been brought forward. Moreover, many pharmaceutical companies have been placing maximum caps on patient copays for insulin or offering other patient assistance programs during this time. International emergencies, such as the current pandemic, may alter the course of insulin prescribing, and further research should examine future trends.”

The study conducted from January 1, 2016, through December 31, 2020, included patients whose data were collected in IQVIA’s National Disease and Therapeutic Index (NDTI), a two-stage, all-payer, nationally representative audit of outpatient care. For that database, about 4,800 physicians each calendar quarter completed a form for 2 consecutive days regarding visits for each of their patients, including diagnoses, treatments, and demographic information.

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