Frequent blood sugar testing was strongly associated with better diabetes control in a large new study that concludes public and private insurers should not be limiting test strip supplies.

Particularly for people with type 1 diabetes, who must test their own blood sugar throughout each day and inject insulin to regulate sugar levels, a cap on the number of test strips they're allowed to use may seriously affect their health, researchers say.

"On the surface it seems crazy to limit tests for people who need them," Dr. Robert Rushakoff, a diabetes expert at the University of California, San Francisco, told Reuters Health.

Roughly one million Americans have type 1 diabetes. Usually diagnosed in childhood or adolescence, it is a lifelong condition caused by the body's failure to produce insulin, a hormone that lets cells use and store glucose.

In type 2 diabetes, the body makes insulin but doesn't use it effectively. Some type 2 diabetics can manage their condition with lifestyle changes and don't require insulin.

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For those who do require it, using insulin means testing a droplet of blood to determine glucose levels, then self-administering insulin to regulate them as needed.

Medicare currently pays for a maximum of three blood-testing strips daily, and private insurers only slightly more, according to Rushakoff, who was not involved in the new study. Those limits have stayed low because the strips are costly, about 60 or 70 cents per strip, he said.

According to the study's lead author Kellee Miller, a biostatistician at the Jaeb Center for Health Research in Tampa, Florida, and her coauthors, some contend there's little evidence that more testing translates to better care that would justify paying for more test strips.

So Miller's team collected data on blood sugar control and frequency of self-testing among more than 20,000 people participating in a registry of type 1 diabetics. About half were under age 18.

The researchers looked at how many times a day participants tested their blood, and also at a marker called hemoglobin A1C, which gives an indication of average blood sugar levels over the span of months.

The higher the percentage, the worse the blood sugar control. A normal A1C reading for someone without diabetes is between four percent and six percent.

In all age groups in the study, testing more frequently was linked to safer blood sugar levels, according to the results published in Diabetes Care.

Those who checked three or four times a day, for example, had 8.6 percent A1C, compared to 7.6 percent for people who checked 10 times a day. Testing more than 10 times a day didn't seem to bring any added benefit.

The American Diabetes Association (ADA) encourages people with diabetes to aim for seven percent A1C or lower to remain in a healthy range.

"One percent for A1C is a huge difference," said Miller. Poor control of blood sugar has short and long term risks, including kidney disease and nerve damage.

Getting extra test strips for patients who need them is a lengthy process involving a lot of paperwork. "On a daily basis I get faxes to justify the increased number of strips, and I have to send in chart notes for every single one of those patients," Rushakoff said.

"What's so strange and disturbing about this, it's not like people want to be doing this more often," because finger pricks are painful, he added. "If they only had to check once or twice a day, they would, but testing more is good for them."

The ADA currently recommends all people with diabetes who use insulin test themselves at least three times daily.

That minimum may need to be higher, especially for people with type 1 diabetes who are at a greater risk for low blood sugar, according to Rushakoff.

"Absolute minimum testing is every time you eat, so three times a day, but most people would want to be checking at least 4 times per day," he said. Rushakoff also recommends to his patients check that they check before they exercise and before driving a car, which soon adds up.

"We are hopeful that future guidelines will better reflect our current understanding, from this study and others," Miller said.

But just testing more frequently won't automatically help people manage their diabetes, she cautioned.

"If you check your blood sugar and don't do anything with that number, you're not going to see any difference," Miller said. The next, and most important, step is to regulate insulin dosage and timing of snack and meals.

"There's more to life than checking blood sugars," said Rushakoff. "It's what you do with that data that matters."