Lean Type 2 Diabetes in African Adults May Be a Distinct Disease

Type 2 diabetes (T2D) is often framed as a disease of excess weight, but a multicohort analysis of more than 3300 African adults, published in Diabetologia, challenges that assumption—and with it, the one-size-fits-all treatment approach.^1,2

The study found that adults who are lean and those who are overweight or obese follow divergent complication paths, adding to evidence that lean T2D may be a biologically distinct phenotype driven by insufficient insulin secretion rather than insulin resistance. For pharmacists, it raises a pointed question about whether standard therapy fits a large subset of patients.^1,2

A Large, Overlooked Population

Nearly 40% of African adults with T2D are lean, which is defined as a body mass index (BMI) below 25 kg/m², compared with roughly 10% or fewer in most high-income countries. That amounts to an estimated 10 million lean patients across the continent who do not fit the standard clinical picture. The authors argue that, in these patients, the core problem is a shortage of insulin, not a diminished response to it.^2,3

Same Treatment, Different Biology

Guidelines in most African countries, adapted from World Health Organization recommendations, direct clinicians to initiate therapy with metformin or a sulfonylurea regardless of BMI or underlying mechanism. The authors note that insulin-sensitizing agents may not address the underlying insulin deficiency in patients who are lean, potentially leaving glucose suboptimally controlled—a treatment mismatch whose downstream consequences had not previously been investigated.^1,2

Felix Chilunga, MD, MSc, PhD, the study's senior author and an assistant professor in the Department of Public and Occupational Health, cautioned that the findings are not a signal to change prescribing yet. "We would not advise any change in drug treatment at this stage," he said. "The purpose of our work is to raise awareness and call for trials on this mismatch. We are highlighting the issue so that a trial may be conducted to establish what works best for these patients."

Divergent Complication Patterns

Pooling harmonized data from the Africa America Diabetes Mellitus and Research on Obesity and Diabetes among African Migrants cohorts, the investigators found that patients who were lean had a higher prevalence of diabetic retinopathy (pooled prevalence ratio [pPR] 1.36; 95% CI, 1.13-1.63) and stroke (pPR 1.41; 95% CI, 1.01-1.99). By contrast, patients who were overweight or obese had higher rates of hypertension (pPR 0.77 for lean; 95% CI, 0.71-0.85) and greater 10-year cardiovascular disease risk (pPR 0.85 for lean; 95% CI, 0.74-0.97). Chronic kidney disease prevalence did not differ between groups. Body fat percentage accounted for most of the observed differences—up to 92% in one outcome.¹

What It Means for Pharmacists

The divergence has practical implications for monitoring. The pattern suggests that pharmacists who are caring for patients of African descent may want to weigh microvascular surveillance—eye and vision screening—more heavily in leaner patients, whereas cardiovascular and blood pressure risk looms larger in patients with a higher BMI. The authors are careful to note the design is cross-sectional and cannot establish causality, and they call for targeted clinical trials to define the best diagnostic, screening, and treatment strategies for this group. Chilunga also cautioned that there is no reason to assume the mismatch stops at Europe's border, given that people of African descent in Europe are often treated by guidelines written for the higher-BMI form of the disease.^1,2

Chilunga suggested the split should sharpen where surveillance is focused. "We would suggest increasing the intensity of screening for microvascular complications in lean patients, particularly retinopathy, as these patients appear healthier in general and their complications may be overlooked," he explained. "In patients with overweight or obesity, blood pressure and cardiovascular risk remain the priority."

REFERENCES

1. Esmail S, Hayfron-Benjamin C, Darko SN, et al. Divergent complication patterns of type 2 diabetes in African individuals who are lean versus overweight or obese: a multi-cohort analysis. Diabetologia. Published online August 23, 2026. Accessed September 1, 2026. doi:10.1007/s00125-026-06830-2

2. Why one size doesn't fit all: study indicates type 2 diabetes operates differently across weight profiles. News release. Amsterdam University Medical Center. August 24, 2026. Accessed September 1, 2026. https://www.eurekalert.org/news-releases/1140880

3. Ogunjobi TT, Adeyanju SA, Akinwande KG, et al. Improving the prevention and treatment of lean type 2 diabetes in sub-saharan Africa: A review. Euro J Sus Devel Res. 2025;9(2):em0287. doi:10.1007/s00125-026-06830-2