Prevalence and Temporal Trends of Type 2 Diabetes Mellitus Among Adults in Cameroon: A Systematic Review and Meta-analysis

For decades, the story of diabetes in many parts of Africa was one of rarity. Type 2 diabetes, a condition where the body struggles to manage sugar in the blood, was long thought to be a disease of wealth and industrialized nations, rarely seen in rural villages or developing economies. However, as countries undergo rapid changes—cities grow, diets shift toward processed foods, and people live longer lives—the landscape of health is transforming. This shift, known as the epidemiological transition, means that conditions once considered uncommon are now rising sharply across Sub-Saharan Africa. Understanding exactly how widespread this disease has become in specific countries is vital, not just for counting cases, but for planning how to protect communities. Without accurate numbers, health systems cannot prepare the screening programs, treatments, or prevention strategies needed to stop the disease from overwhelming families and hospitals.

In Cameroon, a country in Central Africa with a mix of bustling cities and remote rural areas, the true scale of this diabetes crisis has been difficult to pin down. Previous reports offered conflicting pictures, with some studies suggesting the disease was rare and others hinting at a growing problem. To cut through this confusion, a team of researchers from universities and health organizations across Brazil, India, Mozambique, Turkey, Kenya, and Cameroon came together to conduct a massive review of all available scientific evidence. They did not simply look at one study; they gathered data from eleven different research projects that had surveyed nearly 21,000 adults across the country over several decades. By combining these separate pieces of information, they aimed to create a single, clear estimate of how many adults in Cameroon are living with type 2 diabetes and to see how this number has changed over time.

The researchers carefully selected only studies that looked at regular people living in communities, rather than people in hospitals or specific groups like university students, to ensure their findings reflected the reality of the general population. They looked for data collected between 1997 and 2021, a period that covers significant social and economic changes in the region. When they pooled the results together, they found that approximately 3.5 percent of adults in Cameroon have type 2 diabetes. This means that roughly one in every 28 adults is affected. While this number might seem modest compared to some other parts of the world, the researchers discovered that the situation is not the same everywhere. The data showed a wide range of estimates across different studies, suggesting that in some specific communities, the rate could be as low as less than one percent, while in others, it could be as high as 16 percent. This variation highlights that the burden of the disease is not evenly distributed and depends heavily on local conditions.

One of the most striking patterns the team uncovered was the strong link between age and the disease. The risk of having diabetes rises sharply as people get older. Among adults younger than 45, the prevalence was found to be around 2 percent. However, for those aged 55 and older, the rate jumped to 11 percent. This aligns with what is known about how the disease develops, as the body's ability to manage blood sugar naturally declines with age, and the effects of a lifetime of lifestyle choices accumulate. Surprisingly, the researchers found that where a person lived—whether in a city or the countryside—did not make a statistically significant difference in these specific studies. This challenges the common assumption that diabetes is strictly an urban problem, suggesting that rural areas in Cameroon may be facing a similar, if not identical, burden.

The study also looked at how the situation has evolved over the last few decades. The data revealed a clear upward trend. In the late 1990s, when the earliest studies in the review were conducted, the prevalence of diabetes was estimated at just 1 percent. By the time studies conducted after 2015 were analyzed, that figure had risen to 5 percent. This steady increase suggests that the disease is becoming more common as time goes on, likely driven by the same forces of urbanization and lifestyle changes affecting the entire region. The researchers noted that while the number of cases is growing, the ability to diagnose and manage the disease remains a challenge, particularly in areas with limited access to healthcare.

Despite the clear evidence of a rising tide, the researchers emphasized that their work also revealed significant gaps in knowledge. The studies they reviewed were not evenly spread across the entire country; many were concentrated in specific regions, leaving large parts of Cameroon without recent, reliable data. Furthermore, the methods used to measure diabetes varied from study to study, which made it difficult to compare results perfectly. The team concluded that to truly understand and fight this growing epidemic, Cameroon needs a standardized system for tracking diabetes that covers the whole nation, from the largest cities to the most remote villages. Without such a system, it will be impossible to know exactly who is at risk or to ensure that prevention efforts reach the people who need them most. The findings serve as a call to action, urging health officials to strengthen surveillance and expand early detection programs to address a public health challenge that is quietly but steadily reshaping the health of the nation.