Distribution of ApoE Gene Polymorphism and Its Association with the Lipid Profile Among Type 2 Diabetes Mellitus Black South Africans

Background: ApoE is a major regulator of lipid metabolism and glycaemic control. The aim of the current study is to investigate the ApoE gene polymorphisms among Black South Africans with and without type 2 diabetes mellitus (T2DM) and associate them with their lipid profile. Methods: A cross-sectional case–control study was conducted among 107 participants, divided into two groups: patients with T2DM (n = 65) and non-diabetic controls (n = 42). Blood samples were collected for analysis of glycated haemoglobin, lipid profile, nitric oxide, high-sensitivity C-reactive protein and DNA genotyping using the MALDI-TOF. Continuous variables were analysed using Student’s t-test or one-way analysis of variance (ANOVA). Genotype and allele frequencies were compared using Fisher’s exact tests. Results: The ApoE3 allele was the most prevalent among both groups, observed in 55.47% in T2DM patients and 52.38% in the non-diabetic group, followed by E4 and E2. HWE analysis revealed a deviation from equilibrium [χ2 (3) = 9.137, p = 0.0275]. TG levels differed significantly across ApoE alleles (F = 3.68, p = 0.03), with higher TG concentrations observed among E3 allele carriers and E4 allele carriers. Poor glycaemic control (HbA1c ≥ 7.0%) predominated across all ApoE alleles. Among E3 allele carriers, 75.0% of participants exhibited poor glycaemic control, whereas only 25.0% achieved good glycaemic control (p = 0.002). Conclusions: ApoE polymorphisms are associated with allele-specific heterogeneity in lipid metabolism and glycaemic control among individuals with T2DM, underscoring the complex, context-dependent role of genetic variation in metabolic dysregulation within African populations.