The cost-effectiveness of insulin is being questioned after prices of the crucial diabetes drug have tripled in just 10 years.
New research shows that since 2010 the per-person spending on insulin has been higher than per-person spending on all other diabetes drugs combined.
The price hike has made experts question how worthwhile the drug is compared to other therapies that also reduce blood sugar levels.
Researchers from the University of Melbourne in Australia and the University of Michigan in the US analysed figures from almost 28,000 people who had received treatment over an 11-year-period.
Professor William Herman, lifetime diabetes care researcher at Michigan University, said: "In the United States, the more than three-fold increase in the cost of insulin over the past decade is alarming.
"It is a burden to both patients and payers and may deny some people access to a lifesaving therapy."
Over the 11-year- period where usage went from 171 mL to 206 mL as prescribed doses went up to match an increasing global obesity as well as recommendations to lower sugar levels.
One in four participants used insulin to control their blood sugar and two thirds took oral medication whilst some used new injectable drugs designed to complement oral drug use.
Insulin injections keep people with Type One diabetes alive, taking multiple injections often starting in childhood.
Insulin is prescribed to adults with advanced Type Two diabetes to control blood sugar after other methods and medications have failed to reduce the blood sugar levels.
Prof Herman, co-author of the study published in the Journal of the American Medical Association, said: "Although the newer, more expensive insulin analogy appear to have incremental benefits compared to older, less expensive insulin preparations, their premium price requires us to ask whether they are really necessary and if so, for whom?"
Experts concluded that there must be a shift in focus to consider whether the costs outweigh the benefits.
Professor Dr Philip Clarke, co-author of the study added: "What our study shows is how quickly things can change and why there is a need to focus on the costs as well as the benefits when deciding treatment options for people with diabetes."