Researchers warn that type 2 diabetes could affect millions more people in the coming decades after a study published this month revealed the disease is rising far faster among people in sub-Saharan Africa than previously thought.

Take 51-year-old security guard Sibusiso Sithole, for example. Being diagnosed with type 2 diabetes came as a shock, he said, because he walked six miles to and from work every day and never thought his weight was a problem.

Then his wife noticed changes in his health.

Since his diagnosis 13 years ago, Sithole has been on a rigorous treatment for diabetes and high blood pressure.

“I have to take six … medications every day,” he said.

Diabetes is a condition in which the body struggles to turn food into energy due to insufficient insulin. Without insulin, sugar stays in the blood instead of entering cells, leading to high blood-sugar levels. Long-term complications include heart disease, kidney failure, blindness and amputations.

The International Diabetes Federation estimated in 2021 that 24 million adults in sub-Saharan Africa were living with the condition. Researchers had projected that by 2045, about 6% of sub-Saharan Africans — over 50 million — would have diabetes.

The new study, published this month in the medical journal The Lancet, suggested the actual percentage could be nearly double that.

By tracking more than 10,000 participants in South Africa, Kenya, Ghana and Burkina Faso over seven years, researchers found that poor eating habits, lack of health care access, obesity and physical inactivity are key drivers of diabetes in Africa.

Dr. Raylton Chikwati, a study co-author from the University of Witwatersrand in South Africa, said another risk factor is living in or moving to the outskirts of cities, or “peri-urban areas.”

“Access to health care, you know, in the rural areas is a bit less than in the urban areas,” Chikwati said, adding that increased use of processed foods in the peri-urban areas was a problem.

Palwende Boua, a research associate at the Clinical Research Unit of Nanoro in Burkina Faso, said long-term studies are rare in Africa but essential to understanding diseases.

“Being able to have a repeated measure and following up [with] the same people … is providing much more information and much valuable information,” Boua said, “rather than having to see people once and trying to understand a phenomenon.”

Boua is preparing a policy brief for Burkina Faso’s government to assist in the fight against diabetes.

For Sithole, managing his diabetes has been a long journey. But with treatment and lifestyle changes, he has regained control over his health.

“What I can tell people is that they must go and check — check the way they eat — because that time I was having too much weight in my body,” he said. “I was wearing size 40 that time. Now I’m wearing size 34.”

Experts stressed that Africans should get their blood-sugar level tested and seek treatment when diabetes is diagnosed.