Background <p>Achieving optimal glycemic control in patients with type 2 diabetes remains a global clinical challenge, particularly in ethnically diverse regions such as Malaysia.</p> Objective <p>To evaluate the associations between sociodemographic factors, BMI treatment types, comorbidities and diabetes duration with glycemic control among Malaysia’s three major ethnic groups of adults with type 2 diabetes.</p> Methods <p>A retrospective review of 642 patient records with equal ethnic representation (<i>n</i> = 214 each) was conducted at Hospital Sultan Abdul Aziz Shah, from June 2024 to May 2025. Patient data, including age, gender, ethnicity, BMI, comorbidities, diabetes duration, and pharmacological treatment, were collected. Haemoglobin A1c (HbA1c) levels over time were analysed using linear mixed models, adjusting for demographic and clinical covariates.</p> Results <p>The median age of the patients was 65 years, with males predominating: Malays (<i>n</i> = 115, 53.7%), Chinese (<i>n</i> = 128, 59.8%), and Indians (<i>n</i> = 128, 59.8%). Approximately 2.3% (<i>n</i> = 15) were underweight, 36.3% (<i>n</i> = 233) had normal weight, 35.2% (<i>n</i> = 226) were overweight, and 26.2% (<i>n</i> = 168) were obese. About 53.6% received combination therapy. Hypertension only was present in 6.6% (<i>n</i> = 42), dyslipidemia only in 15.4% (<i>n</i> = 99), both conditions in 75.2% (<i>n</i> = 483), and 2.8% (<i>n</i> = 18) had no comorbidities. About 19.4% (<i>n</i> = 124) had a diabetes duration of &lt; 5 years, 35.5% (<i>n</i> = 228) had 6 to 10 years, 24.1% (<i>n</i> = 155) had 11 to 15 years, and 21.0% (<i>n</i> = 135) had ≥ 16 years. Age, gender, ethnicity, and treatment were significantly associated with HbA1c levels (<i>p</i> &lt; 0.05). However, only age, gender and treatment showed a significant association with HbA1c changes over time (<i>p</i> &lt; 0.05). Notably, older age, females, Chinese ethnicity, and being on monotherapy were associated with better glycemic outcomes.</p> Conclusion <p>Age, gender, ethnicity, and treatment are key determinants of glycemic control in Malaysian adults with type 2 diabetes. Personalised treatment strategies, focusing on younger patients, males, those of Malay or Indian ethnicity, and the selective use of monotherapy, may improve glycemic outcomes and reduce complications.</p>