Atypical diabetes subtypes in Black African populations

Atypical diabetes subtypes and presentations are disproportionately prevalent in populations of African and Asian ancestry. This review discusses the epidemiology, clinical presentation, aetiopathogenesis and management of four atypical diabetes subtypes commonly reported in Black African populations. These are ketosis-prone diabetes (KPD), fibrocalculous pancreatic diabetes (FCPD), type 2 diabetes in individuals without overweight or obesity, and malnutrition-related diabetes (MRD). The review summarises current insights into these atypical diabetes subtypes in Black African populations and provides practical recommendations to guide their precision diagnosis and management in the African region. These four atypical diabetes subtypes exhibit phenotypic features that diverge from those of classical type 1 and type 2 diabetes. KPD is characterised by unprovoked, transient, index episodes of diabetic ketoacidosis, often in the absence of markers of islet cell autoimmunity, with frequent subsequent insulin independence and diabetes remission. FCPD typically presents in young lean individuals, with a strong male preponderance and with radiological evidence of pancreatic calcifications, reduced beta cell reserve and severe hyperglycaemia without ketosis. Type 2 diabetes in individuals without overweight or obesity is characterised by normal BMI with a trend towards low levels of markers of visceral adiposity, insulin resistance and an exaggerated beta cell secretory dysfunction. MRD is associated with a previous and persistent history of undernutrition, with features of undernutrition such as stunting and BMI <18.5 kg/m2, resistance to diabetic ketoacidosis, no evidence of visceral or ectopic adiposity, and severe beta cell secretory dysfunction. The high prevalence and heterogeneous presentation of these atypical forms of diabetes in African populations highlight the urgent need for enhanced collaborative research to better define their epidemiology, improve diagnostic accuracy and develop context-appropriate management strategies tailored to diverse African populations.