Background As a result of the chronic nature of type 2 diabetes mellitus (T2DM), its complications, and treatment complexity, patients should have a comprehensive knowledge of various aspects of T2DM management and follow-up. The study aimed to assess T2DM patients' knowledge of disease complications and their screening strategies and the management targets for glucose, lipids, blood pressure, and body weight. Methods This was a cross-sectional and questionnaire-based study including 205 adult patients with T2DM from November 2023 to March 2024. The patients were randomly selected at one tertiary endocrine center and the outpatient clinics of three teaching hospitals in Basrah, southern Iraq. Social and disease-related data were collected. Another 18 T2DM-related questions were designed to assess the patients' knowledge about the aim of treatment; T2DM complications and their screening; the recommended targets for glycemic, lipid, and blood pressure control; and the recommended exercise and weight loss. We gave one point for each correct answer and considered a final score of 10/18 as adequate. Results Of a total of 205 patients, 109 (53.2) were women. The mean age for patients was 48.7 ± 13.1 years. Based on the patients' responses, 107 (52.2%) had adequate knowledge about T2DM. Questions about the target fasting and post-prandial capillary blood glucose, HbA1c target and frequency, and naming the current treatment were the most correctly answered questions (80.9%, 73.1%, 68.7%, and 72.6%, respectively). Questions about the lipid target, definition of hypoglycemia, and ideal lifestyle for T2DM (exercise and bodyweight loss) were least correctly answered. Patients younger than 40 years old, being a man, with a higher educational level, and T2DM duration of more than five years had significantly higher T2DM knowledge. Conclusions Only half of the patients had adequate T2DM knowledge. Better degree of knowledge was particularly observed in patients with younger age, male gender, higher educational level, and longer T2DM duration.There is a need to promote diabetes education strategies for people with T2DM.