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

Abstract

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 ²) and normal-weight (body mass index of 18.5–24.9 kg/m ²) 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 ², 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% versus 28.2%, p = 0.04) and lower median visceral fat levels [2 (1–3) versus 6 (4–7), p < 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) versus 0.82 (0.39–1.50) nmol/l, p = 0.04] and a higher prevalence of insulin deficiency (66.7% versus 31.4%, p = 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.

Plain language summary

Type 2 diabetes in underweight Ugandans

In this study that investigated how type 2 diabetes presents in adult Ugandans with normal body mass index, about one in ten were underweight. Type 2 diabetes in these individuals was characterized by a low prevalence of hypertension, lower body fat levels, and features of reduced insulin production by the pancreas.