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Among treatments for chronic conditions, diabetes drugs aren’t nearly as sexy as, say, Sovaldi, last year’s breakthrough hepatitis C drug that offers a cure for the chronic liver infection at a price approaching six figures.

Yet an estimated 29 million Americans have diabetes — about 10 times the number with hepatitis C — and many of them will take diabetes drugs for the rest of their lives. Cost increases for both old and new drugs are forcing many consumers to scramble to pay for them.

“Every week I see patients who can’t afford their drugs,” says endocrinologist Joel Zonszein, director of the clinical diabetes center at Montefiore Medical Center in New York.

Many people with diabetes take multiple drugs that work in different ways to control their blood sugar. Although some of the top-selling diabetes drugs, such as metformin, are modestly priced generics, new brand-name drugs continue to be introduced. They may be more effective and have fewer side effects, but these advantages often come at a price. In 2014 for the fourth year in a row, spending on diabetes drugs was higher on a per-member basis than it was for any other class of traditional drug, according to the Express Scripts Drug Trend Report. Fewer than half of the prescriptions filled for diabetes treatments were generic.

“The cost of diabetes treatment has been increasing pretty rapidly,” says Glen Stettin, senior vice president for clinical, research and new solutions at Express Scripts, which manages the pharmacy benefits for many companies.

Last year the cost of Humalog, a fast-acting insulin approved by the Food and Drug Administration in 1996, increased 36.1 percent, more than any other of the top 10 traditional drugs based on spending, according to the Express Scripts report.

A number of factors contribute to the trend, Stettin says — because of price increases for brand-name drugs, because people are often on multi-drug regimens and because more people with diabetes are receiving treatment.

An analysis of per-capita health-care spending in 2013 for people with diabetes found average costs were $14,999, roughly $10,000 higher than for people without the disease. The study, by the Health Care Cost Institute, examined insurance claims of nearly 40 million people younger than 65 who had employer-sponsored insurance.

Higher costs for people with diabetes were also reflected in higher out-of-pocket payments. They spent $1,922 on average for deductibles, co-payments and coinsurance in 2013, compared with $738 for people without diabetes.

Zonszein recalled how the costliness of care played out this month for one of his patients. She asked him about switching to a less expensive insulin drug than Lantus, which costs her $160 a month. In addition to that drug, the 69-year-old woman takes Janumet, which works in a different way from insulin to lower blood sugar, and she is using other drugs to control her high cholesterol and high blood pressure.

Zonszein’s patient has drug coverage through Medicare. But because of her large purchases of medications, she has reached what is called the “doughnut hole” when many Medicare beneficiaries are responsible for paying a larger percentage of drug costs. In 2015, the coverage gap starts when both the patient and her drug plan have spent $2,960 on covered drugs, and it ends when spending reaches $4,700, the out-of-pocket maximum. At that point, catastrophic coverage kicks in and the drug plan picks up nearly all drug costs for the remainder of the year. (The coverage gap is shrinking as part of the federal health law.)

Zonszein and his patient decided that since her diabetes is well controlled on her current drug regimen and she is just two months away from leaving the doughnut hole, she would dig into her savings to remain on her current medications.

“This is becoming year over year more of a problem,” he says.

Insurers and pharmacy benefit managers have increasingly devoted time and effort to managing patients’ prescription drugs. Requiring patients to try an older, cheaper drug before approving a newer one is common practice, as are rules that require providers to get approval before prescribing pricey drugs.

Diabetes occurs when the body can’t control the amount of sugar in the blood because of problems making or responding to the hormone insulin, which allows cells to use sugar (glucose) for energy. High levels of blood sugar can cause damage to the heart and blood vessels, nerves, kidneys, eyes and feet, among other things. About 90 percent of people with diabetes have Type 2, which is linked to lifestyle factors such as obesity and inactivity. Type 1, once called juvenile diabetes, commonly develops in childhood.

Insulin was considered a wonder drug when it was discovered in 1921. It remains a mainstay of treatment for millions of patients, yet there are still no generic forms of insulin available.

Incremental improvements in insulin drugs have extended their patent protection in some cases, and some older versions of insulin are no longer sold in the United States, says Jeremy Greene, a professor of medicine and the history of medicine at Johns Hopkins University.

Increasingly, drug manufacturers are developing close copies of the biologic drugs that are made with living cells. These “biosimilar drugs” may provide some relief from high costs. The Food and Drug Administration recently established a regulatory pathway for biosimilar drugs to gain approval, and drug experts suggest that as insulin patents expire, biosimilar insulins could reduce the price by up to 40 percent.

This column is produced through a collaboration between The Post and Kaiser Health News, an editorially independent news service that is a program of the Kaiser Family Foundation. To submit a question, go to kaiserhealthnews.org/contact-insuring-your-health.