Phenotypic characterization of nonautoimmune diabetes in adult Ugandans with low body mass index.

BACKGROUND

Type 2 diabetes is common in relatively lean individuals in sub-Saharan Africa. It is unclear whether phenotypic differences exist between underweight and normal-weight African patients with type 2 diabetes. This study compared specific characteristics between underweight (body mass index <18.5 kg/m) and normal-weight (body mass index of 18.5-24.9 kg/m) adult Ugandans with new-onset nonautoimmune diabetes.

METHODS

We collected the demographic, clinical, anthropometric, and metabolic characteristics of 160 participants with nonobese new-onset type 2 diabetes (defined as diabetes diagnosed <3 months, body mass index <25 kg/m, and absence of islet-cell autoimmunity). These participants were categorized as underweight and normal weight, and their phenotypic characteristics were compared.

RESULTS

Of the 160 participants with nonobese new-onset type 2 diabetes, 18 participants (11.3%) were underweight. Compared with those with normal weight, underweight participants presented with less co-existing hypertension (5.6% 28.2%,  = 0.04) and lower median visceral fat levels [2 (1-3) 6 (4-7),  < 0.001], as assessed by bioimpedance analysis. Pathophysiologically, they presented with a lower median 120-min post-glucose load C-peptide level [0.29 (0.13-0.58) 0.82 (0.39-1.50) nmol/l,  = 0.04] and a higher prevalence of insulin deficiency (66.7% 31.4%,  = 0.003).

CONCLUSION

This study demonstrates that nonautoimmune diabetes occurs in underweight individuals in sub-Saharan Africa and is characterized by the absence of visceral adiposity, reduced late-phase insulin secretion, and greater insulin deficiency. These findings necessitate further studies to inform how the prevention, identification, and management of diabetes in such individuals can be individualized.