The South Korean appetite for fast food and other unhealthy foods is showing its dark side as the number of Koreans suffering from diabetes shot up 24.6 percent in 2015 from five years earlier.

The study by the National Health Insurance Service (NHIS) found that 2.52 million Koreans now have diabetes –this compared with 2.02 million posted in 2010.

The problem is becoming an additional burden on public health care expenditures in a country with one of the most affordable healthcare systems.

According to the NHIS, expenditures rose 33.3 percent to US$1.5 billion, accounting for 3.2 percent of the combined health-insurance spending.

Of those with diabetes, based on gender, 55 percent are male.

South Koreans become most vulnerable to diabetes in their 40s, the study found, while under 30-years-old accounted for 4.3 percent of the patients, the share jumped to 11.5 percent for 40-somethings in the most recent data.

The NHIS said that people in their 50s, 60s and 70s made up 25.7 percent, 27.9 percent and 22.8 percent of those with diabetes respectively.