Monogenic diabetes in South Africa: clinical clues and lessons from seven cases

Monogenic diabetes is an important but under-recognised cause of diabetes mellitus, particularly in settings with limited access to genetic testing. A retrospective case series of seven individuals with genetically confirmed monogenic diabetes managed at tertiary academic centres in Cape Town is described to emphasise that these conditions occur in South Africa. Patients with mutations associated with maturity-onset diabetes of the young, neonatal diabetes, mitochondrial diabetes, and syndromic insulin resistance were identified. Diagnostic reassessment was prompted by early-onset diabetes, preserved endogenous insulin secretion, negative islet autoantibodies, syndromic features, or unexpected treatment responses. Genetic confirmation had important implications for treatment, prognosis, and family screening. This case series demonstrates that monogenic diabetes occurs across a broad phenotypic spectrum in South Africa and that recognition in routine clinical practice leads to meaningful changes in management, surveillance, and family counselling.