Diabetes is a disease with high prevalence and causes heavy economic burden. Mental and physical health are tied together and their interaction determines one's health or sickness. Early maladaptive schemas (EMSs) are suitable indicators of mental health. We investigated the association between EMSs and glycaemic control in type 2 diabetes mellitus (T2DM) patients. We conducted a cross-sectional study in 2021 on 150 patients with T2DM. We used two questionnaires a demographic data questionnaire, and a Young Schema Questionnaire 2 - Short Form for gathering the data. We also performed laboratory tests on our participants and used the results of fasting blood sugar and haemoglobin A1 c to evaluate glycaemic control. Most of our participants were females (66%). Most of our patients were 41-60 years old (54%). There were only three single participants, and 86.6% of our individuals did not have a university degree. Total mean ± SD for EMSs score was 192.45 ± 55.66; self-sacrifice (19.09 ± 4.64) and defectiveness/shame (8.72 ± 4.45) had the highest and lowest EMSs scores, respectively. None of the demographic data had any significant impact on EMSs scores or glycaemic control, but generally, younger patients with higher levels of education had better glycaemic control. Participants with higher scores for defectiveness/shame and insufficient self-control had significantly worse glycaemic control. Mental and physical health are tied together, and paying attention to psychological aspects in prevention and management of physical disorders is crucial. EMSs, especially defectiveness/shame and insufficient self-control are associated with glycaemic control of T2DM patients.