Type 2 diabetes is commonly linked to excess body weight.
However, recent research indicates that this familiar association doesn’t hold true for millions of people in Africa who develop the condition while remaining lean.
A team of scientists from Amsterdam UMC and the University of Ghana discovered that the biological pathways leading to type 2 diabetes may vary based on a person’s body mass index (BMI).
Their findings highlight that some lean individuals might require different treatment approaches.
Diabetes occurs when the body can’t maintain blood sugar levels within a healthy range. Normally, insulin—a hormone produced by the pancreas—assists in moving sugar from the bloodstream into cells, where it provides energy.
In typical cases associated with overweight or obesity, the body often develops insulin resistance. Initially, the pancreas compensates by producing more insulin, but over time, it may fail to keep blood sugar under control.
The new research suggests that in lean African adults, the disease might manifest differently—many may have a pancreas that produces insufficient insulin rather than simply resisting insulin.
This distinction is crucial because current international guidelines for managing type 2 diabetes are largely based on studies from populations where excess weight is a primary factor. In wealthier nations, about 90% of people with type 2 diabetes are overweight, the researchers noted.
In Africa, though, the pattern differs significantly. Nearly 40% of African adults with type 2 diabetes are lean, and in some rural areas, including parts of Ghana, the figure can reach 60%.
Lead author Sabrina Esmail estimated that around 10 million lean individuals with diabetes in Africa might not fit the traditional understanding of the disease. For many in this group, inadequate insulin production may be more relevant than insulin resistance.
The researchers analyzed data from over 3,300 African adults with type 2 diabetes from Ghana, Nigeria, and Kenya, along with African individuals living in Europe. They examined differences in body size, insulin-related biology, and diabetes complications.
The results showed that lean and overweight patients did not simply have the same disease presenting differently due to body weight. Their complication patterns also varied, indicating different underlying biological mechanisms.
Lean patients were more prone to diabetic retinopathy, leading to damage in small blood vessels in the eyes, and they experienced higher rates of stroke. Those with higher body weight were more likely to have high blood pressure and cardiovascular issues.
Chronic kidney disease appeared at similar rates in both groups. Many of these differences could be explained by body fat levels.
The causes behind each form of diabetes may differ as well. Excess fat contributes heavily to insulin resistance, whereas some lean individuals might have suffered from poor nutrition during early life or been born with a low birth weight.
This raises important questions about treatment strategies. In many African healthcare settings, both lean and overweight patients are treated with similar guidelines and often receive medications like metformin or sulfonylureas.
While these medications can be effective, they are primarily designed around the typical insulin-resistant form of the disease. For those whose main issue is low insulin production, different treatments might be more appropriate. The researchers advocate for clinical trials specifically targeting lean African patients.
Beyond Africa, previous studies—such as those using the UK Biobank—have found that individuals of African descent tend to develop diabetes at lower BMIs than Europeans. Additionally, African migrants often experience earlier onset and poorer blood sugar control.
Project leader Charles Agyemang emphasized that there’s no reason to believe treatment challenges disappear when African patients migrate to Europe. This raises questions about whether BMI thresholds and guidelines developed mainly from European populations are effective for everyone.
The study, published in Diabetologia, was conducted through collaborations among Amsterdam UMC, the University of Ghana, and other institutions. It contributes to growing evidence that what we label “type 2 diabetes” actually includes several distinct forms of disease that lead to high blood sugar through different biological pathways.
While these findings are significant, they do not yet prove that existing medications are ineffective or harmful for lean African patients. The study identified biological differences and patterns of complications, but targeted treatment trials are needed to determine if therapy adjustments improve outcomes.
The key takeaway is that future diabetes care might need to be more personalized, considering factors like body composition, insulin production, genetic background, early-life nutrition, and other influences before selecting a treatment plan.
If further research supports these conclusions, diabetes management could become more tailored for millions who have largely been underrepresented in past studies.
Until then, patients should continue their prescribed treatments and consult their healthcare providers for any concerns, rather than making unilateral changes to their medication regimes.