Democratic presidential hopeful Bernie Sanders says he's taking a bus from Detroit to Windsor on Sunday to show how Americans are getting "ripped off" by prescription drug prices.

Sanders is expected to join a group of people with type 1 diabetes looking to buy cheaper insulin across the river in Canada.

The international travel plan comes as Sanders ramps up his calls for prescription drug cost controls and a government-run health insurance system ahead of next week’s second presidential debate in Detroit, where he's set to hold a "grassroots" fundraiser Saturday evening.

"At a time when we have an epidemic of diabetes in the United States, going over to Windsor, Ontario, going over that bridge, you're going to be able to buy insulin there for one-tenth of the price that is charged in Michigan and the United States of America," Sanders predicted in a phone interview with The Detroit News.

The Vermont Senator and self-avowed democratic socialist won Michigan’s 2016 primary over eventual Democratic nominee Hillary Clinton but this cycle is facing new competition for progressive voters from others within the 25-candidate field.

Sanders blames pharmaceutical industry profit motives and a lack of federal government oversight for high prescription drug prices.

"We're seeing people all over this country who simply cannot afford the medicine they need or are just paying much more than they should be paying," he said. "And we have to go tell the drug companies that enough is enough."

Insulin prices have “skyrocketed” in the United States in recent years, nearly tripling between 2002 and 2013, according to a recent report from the American Diabetes Association. Between 2012 and 2016 alone, gross spending on insulin doubled, according to the non-profit Health Care Cost Institute.

Many industrialized countries directly negotiate prices with pharmaceutical companies. Here, prices are often dependent upon insurance company negotiations and market forces.

Canada’s national health care system does not cover prescription drugs, but the country’s Patented Medicines Price Review board oversees prices and caps medication at a rate partially based on costs in other countries.

Sanders is a leading advocate for a nationalized health care proposal known as Medicare for All that would eliminate private insurance in favor of a single-payer government system. He said the plan would cap yearly prescription drug bills at $200 and drive down costs by using Medicare to negotiate with drug companies.

The proposal appears relatively popular with Democrats, but a majority of Michigan general election voters oppose strict Medicare for All, according to a July 17-20 poll conducted by Glengariff Group Inc. and commissioned by the Detroit Regional Chamber.

The survey of 600 likely voters found that 53% of self-described independents, who could play a crucial role in a close general election, oppose eliminating private insurance for a single-payer plan.

Asked about those poll numbers, Sanders noted "huge growth in support for the concept" since he introduced Medicare for All four years ago.

"For the overwhelming majority of the American people, we will save them money on their health care bills. Because please, let us never forget, that right across the Canadian border from where you are, the cost of per capita health care is one half of what it is in the United States."

Republican President Donald Trump has bashed Medicare for All, arguing it is a “radical socialist” idea that would cause taxes to “skyrocket” and could jeopardize the traditional health insurance program for seniors.

Sanders estimates his plan would cost between $30 trillion and $40 trillion over 10 years but argues it could reduce health care spending by up to $20 trillion over that span by cutting insurer profits and corporate CEO salaries out of the system.

Several other 2020 Democratic candidates are backing some form of Medicare for All, although some want to retain a private insurance option. Former Vice President Joe Biden wants to expand the Affordable Care Act and add a public option for a government-run health plan.

Sanders has introduced Senate legislation that seeks to reduce prescription drug prices by giving the federal government power to authorize generic versions of name-brand medication if pharmaceutical companies charge more than the median price in five other major industrialized countries, including Canada and the United Kingdom.

He's also sponsored legislation that would allow wholesalers and licensed pharmacists to import cheaper prescription drugs from Canada and eventually other advanced countries.

A handful of states are developing plans to import certain high-priced medications as allowed under a 2013 law, an option endorsed by Trump.

Sanders is expected to travel to Windsor with members of Insulin4All, a group that fights for access to diabetes medication, supplies and care.

Type 1 diabetes is a chronic condition that results when an individual's pancreas is unable to produce enough insulin, leading to high blood-sugar levels that can cause other complications. It’s typically treated by daily insulin shots.

Sanders and Warren, both favorites of the progressive left, will share the debate stage Tuesday night in Detroit. South Bend Mayor Pete Buttigieg of Indiana, former Rep. Beto O’Rourke of Texas, Sen. Amy Klobuchar and others will also compete.

The two-day event will continue Wednesday night with a debate featuring former Vice President Joe Biden, Harris, Booker and seven other candidates.

joosting@detroitnews.com