The United States could cut health care costs significantly and improve care for 4 million people with diabetes significantly if health insurance ownership rates in all states were as high as they now are in the top-performing states.

Researchers talked about state-to-state variations in diabetes care earlier this week, when they released a state health scorecard through the Commonwealth Fund, New York.

The researchers used diabetes care statistics as an indicator for how well states are dealing with serious chronic conditions that often respond well to good medical care.

Even in the 5 states with the highest levels of health insurance ownership — Hawaii, North Dakota, Minnesota, Delaware and South Dakota–only about two-thirds of low-income people with diabetes receive the basic recommended services, such as blood screening, foot exams and eye exams, the researchers report.

But that percentage was far higher than the national average.

Across the nation, only 39% of people with diabetes receive the basic recommended services, the researchers report.

If screening rates for people with diabetes in all states reached levels achieved by the top states, 3.6 million more adult diabetics would receive 3 recommended services–eye exam, foot exam and hemoglobin A1c test–to help prevent serious diabetes complications, the researchers estimate.