MEXICO CITY -- With each bite into a greasy taco and slurp of a sugary drink, Mexico hurtles toward what health experts predict will be a public health crisis from diabetes-related disease.

A fifth of all Mexican women and more than a quarter of men are believed to be at risk for diabetes now. It’s already the nation’s No. 1 killer, taking some 70,000 lives a year, far more than gangster violence.

Public health experts blame changes in lifestyle that have made Mexicans more obese than anywhere else on Earth except the United States. They attribute changes to powerful snack and soft drink industries, newly sedentary ways of living and a genetic heritage susceptible to diabetes, a chronic, life-threatening illness.

The results are evident at public hospitals, where those needing treatment for diabetes-related illness, such as blindness and kidney dialysis, clamor for help.

“The first time we came, we had to wait 12 days for my husband to get dialysis,” said Marta Remigio Jasso, who spoke on the grounds of the General Hospital of Mexico, a public unit of the Secretariat of Health. “I slept under my husband’s hospital bed.”

Already, some 150,000 Mexicans receive kidney dialysis, but nearly the same number are denied treatment for lack of insurance, said Dr. Abelardo Avila Curiel, a physician and expert in population studies at one of Mexico’s most prestigious medical centers, the Salvador Zubiran National Institute of Medical Sciences and Nutrition.

“When we project the increase in diabetes and the costs associated with it, the Mexican health system will be overwhelmed. It can’t be paid for. By the year 2020, it will be catastrophic. By 2030, it faces collapse,” Avila said.

Somewhere between 6.5 million and 10 million Mexicans now have diabetes, the Health Secretariat says. While the numbers are fewer than the 20 million who suffer from diabetes in the United States, Mexico carries the seeds of an unfolding tragedy linked both to soaring obesity and shifting demographics that will heavily burden health systems.

“In the next four decades, the population of people 65 years and older will quadruple,” said Manuel Ordorica Mellado, a demographer at the Colegio de Mexico, a public research and teaching institution. “This is vertiginous growth.”

By the middle of the century, Mexico is likely to have 25 million elderly people, he said, equivalent to the nation’s entire population as recently as 1950.

The elderly are among those suffering the worst from diabetes-related illness.

“Diabetes is the primary cause of blindness in Mexico. It’s also the main reason for amputations,” said Carmen Reyes de Ortega, the executive director of the Mexican Diabetes Association, a nonprofit advocacy and educational group.

“The panorama is not good,” Reyes de Ortega continued. “We’ll have a lot of people suffering blindness, with mobility problems and needing dialysis.”

The once-languid pace of Mexican life has undergone radical transformation in recent decades. Crowded urban areas force long commutes on workers, and public security concerns keep them cooped up at home.

Workers who once would return to their homes for long lunch breaks, eating freshly prepared foods, no longer can do that.

“It is practically impossible to go home to eat lunch now,” said Dr. Gabriela Ortiz, a department director at the National Center for Preventative Health and Disease Control. “We ask for food to be delivered to our office. Some employees go out to the taco stands on the corner or to the street markets.”