About a year and a half ago, Robin Collier and her husband, Wayne, were like millions of other Americans: overweight and living with Type 2 diabetes. Despite multiple diets, the couple could not seem to lose much weight. Then Ms. Collier’s doctor told her she was going to need daily insulin shots to control her diabetes. That was the motivation she needed.

“I made up my mind right then and there,” said Ms. Collier, 62, an administrator at an accounting firm in Lafayette, Ind. “I said to myself, ‘I’m not going on insulin. I’m too young to have this disease.’”

Instead, Ms. Collier and her husband entered a study sponsored by a company called Virta Health, one of a new crop of high-tech companies that have designed programs aimed at helping people prevent or even reverse their diabetes.

On the program, patients video-chat with a remote Virta doctor, who consults with their primary care doctor, reviews their blood tests and medical history, and makes diet and drug recommendations. While studies show that a variety of different diets can benefit people with Type 2 diabetes, Virta, based in San Francisco, takes a low-carbohydrate approach, training patients to swap foods like pastries, pasta and sugary snacks for veggie omelets, almonds and salads with grilled chicken and beef.

Every day, patients use an app to upload their blood sugar levels, blood pressure, body weight and other measurements. A health coach, usually a registered dietitian, monitors their data and checks in by phone, text or email to discuss any problems or just to provide daily encouragement.

Today, Ms. Collier has lost 75 pounds and has avoided taking insulin. Her husband has lost 45 pounds and was able to stop two diabetes medications. Both are still in the program, which she called “life changing,” as part of an ongoing clinical trial.

Initial results that examined the program’s impact on 241 Type 2 diabetics, published in the journal JMIR Diabetes in March, found that 56 percent had lowered their blood sugar to nondiabetic levels after 10 weeks. About 90 percent had reduced or stopped their use of insulin altogether, and three-quarters had lost at least 5 percent of their body weight. After six months, 90 percent remained on the Virta program, and most continued to lose weight and improve their blood sugar control.

Martin J. Abrahamson, an endocrinologist at Beth Israel Deaconess Medical Center and an associate professor of medicine at Harvard Medical School who has no financial ties to Virta, said the new study was “a great proof of concept” but that he would like to see longer-term results. Still, he believes that these kinds of digital programs will be critical for patients who need more support than the current model of treatment provides.

“People with diabetes have to manage their diabetes 24 hours a day, seven days a week, 365 days a year,” he said, but most Type 2 diabetics see a doctor four times a year at most. In between those visits, they are largely left on their own — and many end up struggling with their diets, their blood sugar and other complicated aspects of their care. “When you think of the amount of time they actually spend in a health care professional’s office getting counseling and support, it’s negligible.

“Developing remote care models is going to be the key if we’re going to have some sort of impact on improving glucose control for the millions of people with diabetes,” he said. “It’s a much more scalable model than seeing people in a doctor’s office.”

While Virta works with patients who already have Type 2 diabetes, other high-tech programs, like Omada Health, another San Francisco start-up, target the 86 million Americans who have pre-diabetes, which means they have high blood sugar and other major risk factors for the disease. Omada trains people to follow a diet and exercise program that was shown in a large clinical trial sponsored by the National Institutes of Health to lower the risk of progression to diabetes by 58 percent.

To help people stick to their program, the company assigns them to online support groups that meet regularly, and it pairs them with personal health coaches who counsel them through private messages and phone calls.

Such programs aren’t cheap. The out-of-pocket cost for Omada, for example, is about $130 a month. But the program is also covered by health plans such as Kaiser Permanente and Humana, as well as large employers like Lowe’s, Costco and Iron Mountain. Virta’s out-of-pocket cost is $400 a month. But the company offers financial assistance based on a patient’s ability to pay. And it is low or no cost for patients whose employer or health plan sponsors it.

But diabetes is a costly disease — accounting for $176 billion in direct medical costs in the United States alone every year — and digital health companies are betting that they can offset costs for patients and their insurers in the long run.

A large study sponsored by Omada and published in the journal PLOS One in October looked at 1,121 overweight or obese people on the company’s program and found that participants lost an average of 7 percent of their body weight after 26 weeks. The researchers estimated that patients who sustained their improvements could reduce their health care costs by up to $14,000 over 10 years.

Virta was created by a tech entrepreneur, Sami Inkinen, who co-founded the real estate website Trulia in 2004 and sold it a decade later to a rival website, Zillow, for $2.5 billion. Mr. Inkinen was inspired by his own personal brush with metabolic disease. Despite being an endurance athlete and triathlon world champion, he discovered five years ago that he was prediabetic. Eventually he determined that his diet was the culprit: Cutting out sugary foods, sports drinks and refined carbohydrates allowed him to reclaim his health, he said.

Mr. Inkinen secured $37 million in venture capital and recruited a team of doctors, dietitians, nutrition scientists and tech experts to build Virta, whose long-term mission “is to reverse Type 2 diabetes in 100 million people by 2025,” he said.

“I simply thought that millions of people living with Type 2 diabetes deserved better than lifelong and costly ‘management’ of the disease,” he said.

Dr. Robert E. Ratner, the former chief scientific and medical officer for the American Diabetes Association and an adviser to Virta, said that the two-year clinical trial of the program currently underway would provide more data about the extent of Virta’s effectiveness over the long haul.

“We don’t have the final answers by any means,” said Dr. Ratner, who is also a professor at Georgetown University School of Medicine. “But this is a positive step forward to improving the lives of people with diabetes.”