This is the list of what Laura Marston has sacrificed to keep herself alive: Her car, her furniture, her apartment, her retirement fund, her dog.

At 36 years old, she has already sold all of her possessions twice to afford the insulin her body needs every day.

Insulin is not like other drugs. It's a natural hormone that controls our blood sugar levels - too high causes vision loss, confusion, nausea, and eventually, organ failure; too low leads to heart irregularities, mood swings, seizures, loss of consciousness.

For most of us, our bodies produce insulin naturally. But for Type 1 (T1) diabetics like Ms Marston, insulin comes in clear glass vials, handed over the pharmacy counter each month - if they can afford it.

One vial of the insulin Ms Marston uses now costs $275 (£210) without health insurance.

In 1923, the discoverers of insulin sold its patent for $1, hoping the low price would keep the essential treatment available to everyone who needed it.

Now, retail prices in the US are around the $300 range for all insulins from the three major brands that control the market.

Even accounting for inflation, that's a price increase of over 1,000%.

Stories of Americans rationing insulin - and dying for it - have been making national headlines.

The most famous case, perhaps, was 26-year-old Alec Smith, who died in 2017 less than a month after he aged out of his mother's health insurance plan. Despite working full-time making more than minimum wage, he could not afford to buy new insurance or pay the $1,000 a month for insulin without it.

Ms Marston knows the feeling - like most of the diabetics I spoke to, she has experienced frightening lapses in coverage through no fault of her own.

A few years ago, when the small law firm Ms Marston worked for abruptly closed, she found herself without an income and suddenly uninsured.

"I was spending $2,880 a month just to keep myself alive - that was more than I was making even working 50 hours a week," says Ms Marston.

She was forced to leave her home in Richmond, Virginia, to find a new job in Washington DC to ensure she could pay for insulin.

"I sold everything, including my car, and had to give up my dog - he was eight and I had to give him away - and move to DC."

There are any number of reasons why someone might still be uninsured in America - if they don't qualify for employer-sponsored insurance or lose their job like Ms Marston had, for example, or if they cannot afford to pay for a plan on their own.

Ms Marston was diagnosed with T1 diabetes when she was 14. She laughs when recalling how the price of insulin in 1996 - $25 for one vial - was a shock to her.

Two decades later, Ms Marston still uses the same formula of insulin - Eli Lilly's Humalog. Even the packaging is the same.

"Nothing about it has changed, except the price has gone up from $21 a vial to $275 a vial."

It's the same story for Sanofi's Apidra and Novo Nordisk's Novolog.

So who's to blame?

Most patients point the finger at the pharmaceutical companies, who in turn bring up problems with government regulations and insurance providers.

At the heart of the issue is the complex mystery around who pays what for insulin in the US.

There are five terms essential to this discussion - list price, net price, rebates, co-payments and deductibles.

• List price is set by a pharmaceutical company, and in many cases is what uninsured diabetics pay
• Net price is the actual profit the company receives for a drug
• Rebates are discounts on drugs negotiated for insurance companies
• Co-payments are what an insured person pays for a prescription, out-of-pocket
• Deductibles, which can be as high as $10,000, are what insurance policies say must be paid before the insurer picks up the rest

Insurance companies enlist third-party negotiators, called pharmacy benefit managers, to fix discounts with drug manufacturers that in turn result in smaller co-payment prices for their users. Experts say part of the system's problem is a lack of transparency around how these rebates are negotiated and how much actually makes its way to patients.

This system also means that insurers end up with different rates for each drug company, so a brand of insulin that has a minimal co-pay under one insurance could cost the full list price under another.

Ms Marston has been tracking insulin list prices for years. By her calculations, for insulin alone, she'll need close to $7m to live until she's 70 if she pays out of pocket.

"It's led to a situation where I decided I couldn't have kids because I don't feel financially stable enough," Ms Marston says.

But drug manufacturers argue that very few people ever face paying list price.

Eli Lilly said in a statement to the BBC that 95% of people using Humalog in the US pay under $100 a month for their prescription, and that of the 600,000 using Humalog, "about 1,600 people without insurance have not utilised the [assistance] benefits we offer".

Novo Nordisk and Sanofi detailed similar patient assistance programmes in their statements. And several diabetics I spoke to did say that these programmes helped them- if they qualified.

But another advocate, Kristen Daniels, says she was faced with a $2,400 price tag for one month of insulin and because she was technically insured, she couldn't get assistance.

"I called my insurance, I called the manufacturer, and no one could help me because I hadn't reached my deductible," Ms Daniels says.

Pharmaceutical companies have also emphasised that rising list prices did not result in commensurate profits. Eli Lilly's spokesman says their net price has actually gone down in the last five years; Sanofi's said their insulin profits are 25% lower in 2019 than 2012.

According to a report by the American Diabetes Association (ADA) and the University of Southern California Center for Health Policy and Economics, between 2007 and 2016, major brand insulin list prices have increased by 252%, while net prices saw less growth at 57%.

And there are cheaper options in the US for some: WalMart insulin, for example, is a re-branded version of a Novo Nordisk formula which retails for around $25 per vial in most states. But the formula is older, less effective, and some, like Ms Marston, are allergic to it.

This is another key issue in the debate around skyrocketing insulin prices. Each formula works differently for each individual. It takes many T1 patients years to feel comfortable managing their dosing with a particular brand.

Several diabetics I spoke to say they have been forced to switch insulins by their insurance plans - even against the recommendation of their physicians - if they wanted to avoid paying the list price for their preferred brand.

The ADA says this "non-medical switching" is more than an inconvenience - it's potentially dangerous, requiring constant monitoring on the patient's part and consultations with a physician.

Serious or permanent complications like blindness or kidney disease can arise if a diabetic is put through too many extreme sugar highs and lows.

In America, where insurance coverage goes hand-in-hand with employment and options are limited, many T1 diabetics make sacrifices in other parts of their lives to keep affording insulin - whether that's staying with a stressful job or switching insulin formulas at the behest of an insurer.

The expression that comes up again and again in the US T1 community is: "We're hostages".

BBC