Experts believe the diet reprogrammed cells and promotes the growth of new insulin-producing pancreatic cells, which could reduce symptoms of type 1 and type 2 diabetes.
University of Southern California scientists used the Fasting Mimicking Diet (FMD) sold under the brand name ProLon in mice and human cell experiments.
Its five-day ‘fasting with food’ programme features meals ranging from 770 to 1,100 calories per day.
It is low in calories, sugars, and protein, high in good fats, gluten and dairy-free and is sold as soup, energy bars, energy drinks, teas, and supplements.
Experts have said it is safer than the 5:2 diet where people you eat normally for five days and then drink just water for the other two days as it provides the body with the necessary macro and micronutrients.
Professor Dr Valter Longo, director of the USC Longevity Institute said: "Cycles of a fasting-mimicking diet and a normal diet essentially reprogrammed non-insulin-producing cells into insulin-producing cells.
"By activating the regeneration of pancreatic cells, we were able to rescue mice from late-stage type 1 and type 2 diabetes.
"We also reactivated insulin production in human pancreatic cells from type 1 diabetes patients."
Dr Emily Burns, from the charity Diabetes UK, said: "This is potentially very exciting news, but we need to see if the results hold true in humans before we'll know more about what it means for people with diabetes.
"People with Type-1 and Type-2 diabetes would benefit immensely from treatments that can repair or regenerate insulin-producing cells in the pancreas."
In type 1 and late-stage type 2 diabetes, the pancreas loses insulin-producing beta cells, increasing instability in blood sugar levels.
But mice placed on the diet for four days each week regained healthy insulin production, reduced insulin resistance and demonstrated more stable levels of blood glucose.
This effect was seen even for mice in the later stages of the disease.
Professor Longo concluded: "These findings warrant a larger Food and Drug Administration trial on the use of the fasting-mimicking diet to treat human diabetes patients to help them produce normal levels of insulin while improving insulin function.
"Hopefully, people with diabetes could one day be treated with an FDA-approved fasting-mimicking diet for a few days each month and gain control over their insulin production and blood sugar."
The university has licensed the FMD nutri-technology to a Los Angeles-based firm to make ProLon - short for Promote health and Longevity.
The study was published in the journal Cell.