(Reuters Health) - Three in ten adults with type 2 diabetes who need to start taking insulin to lower their blood sugar don’t begin treatment when their doctors tell them to, a recent study suggests.

On average, these patients delay insulin for about two years, researchers report in Diabetic Medicine.

“This matters to patients because insulin therapy is typically offered to patients with high blood sugar levels,” said senior study author Dr. Alexander Turchin of Brigham and Women’s Hospital and Harvard Medical School in Boston.

“If the patient does not start insulin therapy and does not initiate any other changes to bring their blood sugar levels down, their blood sugar can stay high for years, leading to diabetes complications such as blindness, kidney failure and heart attacks,” Turchin said by email.

Globally, about one in 10 adults have diabetes, according to the World Health Organization. Most have type 2 diabetes, which is associated with obesity and aging and occurs when the body can’t make or process enough of the hormone insulin.

Medications as well as lifestyle changes such as improved diet and exercise habits can help manage diabetes and keep symptoms in check. When diabetes isn’t well managed, however, dangerously high blood sugar can eventually lead to blindness, amputations, kidney failure, heart disease and stroke.

While some previous research has found diabetics often fail to start insulin when it’s needed, it’s been unclear how much of this is due to doctors failing to prescribe the medication versus patients refusing to take it, Turchin said.

For the current study, researchers examined data from electronic physician notes at Brigham and Women’s Hospital from 2000 to 2014.

Of the 3,295 patients with diabetes included in the analysis, nearly one third declined a physician’s advice to begin insulin at the time the recommendation was made, researchers report in Diabetic Medicine.

People who initially declined, but ultimately accepted the recommendation to start insulin, started the insulin therapy more than two years later, on average, during which time their blood glucose levels climbed.

Sanofi, which sells insulin products, funded the study.

The study wasn’t a controlled experiment designed to prove whether or how delaying insulin impacts the course of diabetes or patients’ health.

Another limitation is the potential that results from one medical center might not reflect what happens for a broader population of patients, the authors note.

It’s also possible that some patients declined insulin but this wasn’t noted in their medical records, leading the study to underestimate how often this occurs. Patients’ reasons for declining or delaying insulin were unknown.

Some patients might reject insulin because they’re afraid of needles or injections, or because they mistakenly think insulin causes diabetes complications, said Dr. Simon Heller, a diabetes researcher at the University of Sheffield in the UK who wasn’t involved in the study.

“They mistakenly think that insulin is the cause instead of understanding that complications have developed because blood sugar has been high for years,” Heller said by email.

Patients need to understand that insulin can help them quickly feel better and get their diabetes under control, said Dr. Vanessa Arguello, an endocrinologist at the David Geffen School of Medicine at University of California, Los Angeles, who wasn’t involved in the study.

But there’s a lot people can do to minimize the odds that they will need insulin, Arguello said by email.

“The key to avoiding insulin begins with making lifestyle changes early in the disease process – this can be as early as when people are diagnosed with pre-diabetes,” Arguello said. “It is immensely rewarding to see the positive effects form a carbohydrate-controlled diet, exercise, and weight loss on type 2 diabetes control - plus collectively it’s the most inexpensive option for optimal glucose control.”

SOURCE: bit.ly/2fyHvVs Diabetic Medicine, online September 14, 2017.