More than 28,000 people were admitted for inpatient stays in Irish hospitals in just four years due to type 2 diabetes.
The condition is often caused by obesity and lack of exercise.
Between 6,000 and 8,000 people were admitted every year between 2015 and 2018.
They included a total of 148 patients aged between 18 and 25-years-old and 31 children, according to new Freedom of Information figures.
Professor Niall Moyna, from the school of health and human performance in DCU, said he's not surprised by the new statistics.
“This is what we have been expecting from this explosion in obesity and overweight over the last 10 to 15 years,” he said.
“It was a time-bomb that was about to explode but it has exploded and these are the manifestations.
“Type 2 diabetes is primarily because of our lifestyle and it is lack of exercise and poor diet.
“Through changing those we could have profound effect. In fact, there is no reason why anyone should be developing type 2 diabetes – particularly prior to the age of 65 and 70-years-of-age.”
He said the rise of the condition among younger people is of serious concern.
“Type 2 Diabetes is due to a dis-regulation of your sugar so your blood sugar levels are higher than they normally should be and that is probably due to an overconsumption of carbohydrates and sugar and lack of exercise,” he said.
“The sad thing now is it is starting earlier and earlier. It used to be called adult-onset diabetes because it normally occurred in people in their 50s and 60s. We now see it in pre-pubescent and adolescent children.
The figures were released to Newstalk under Freedom of Information legislation.