No Improvement in Blood Glucose Control Among Insulin Users Over 30 Years

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No Improvement in Blood Glucose Control Among Insulin Users Over 30 Years

Among people with diabetes who take insulin, there hasn’t been any significant improvement in blood glucose control over decades, according to a new study published in the journal JAMA Network Open.

There are several possible barriers to optimal blood glucose control among people with diabetes who use insulin — starting with the cost of insulin in the United States. Previous research has shown that rationing insulin — taking less insulin than recommended — is common in the United States, a practice that by definition results in worse blood glucose control. While there have been ongoing talks in Congress about legislation that could help reduce the cost of insulin for all Americans who rely on it, only one major policy change regarding insulin costs has actually become law in recent years. That change, a provision in last year’s Inflation Reduction Act, is actually pretty big news for people affected by it — effective January 1 of this year, people enrolled in a Medicare Part D prescription drug plan must pay no more than $35 out-of-pocket each month for covered insulin products. This cap will also apply to insulin for people who use an insulin pump covered by Medicare Part B starting on July 1, 2023.

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For the latest study, researchers looked at nationally representative data from a total of 2,842 U.S. adults with diabetes who used insulin, covering the period between 1988 and 2020. The researchers were most interested in the proportion of participants who had an A1C level (a measure of long-term blood glucose control) below 7%, and they also looked at disparities in blood glucose control between different racial and ethnic groups.

Few changes in glucose control among insulin users over study period

Overall, the proportion of insulin users who had an A1C level below 7% barely changed during the study period — from 29.2% in 1988-1994 to 27.5% in 2017–2020. The proportion of participants who had very high blood glucose (an A1C level above 10%) also barely changed, with 14.6% of participants falling in this group in 2013-2020. Mexican American participants were less likely than white participants to experience good blood glucose control, and the difference between these two groups increased over time. Factors that were linked to a higher risk for severe hypoglycemia (low blood glucose) included being Mexican American or non-Hispanic Black, not having health insurance, and having a low family income.

“Over the past three decades, glycemic control stagnated and racial and ethnic disparities increased among U.S. adults with diabetes who received insulin,” the researchers wrote. “Efforts to improve access to insulin may optimize glycemic control and reduce disparities in this population.”

Want to learn more about insulin? Read “What Does Insulin Do?,” “Insulin Basics,” and “Everything You Ever Wanted to Know About Injecting Insulin.”

Want to learn more about blood glucose management? See our “Blood Sugar Chart,” then read “Blood Sugar Monitoring: When to Check and Why” and “Strike the Spike II: How to Manage High Blood Glucose After Meals.”

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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