Background: Type 2 diabetes mellitus (T2DM) and cardiovascular disease are long – lasting worsening health issues that greatly impact global illness and death rates. Patient with these accompanying health issues frequently need several medications, resulting in a more complicated medication schedule. The Medication Regimen Complexity Index (MRCI) is an established tool designed to evaluate the intricacy of medication plans based on the types of dosage forms, the frequency of administration and any supplementary instructions. Greater complexity in treatment regimens has been linked to reduced adherence to medication, which can lead to insufficient control of blood sugar levels, a higher risk of heart problems and negative health outcomes. Methods: An observational study was carried out in a hospital involving patients who have been diagnosed with Type 2 Diabetes Mellitus and Cardiovascular Disease. Data were gathered utilizing a systematic data collection form. The complexity of medication schedule was assessed by utilizing the Medication Regimen Complexity Index (MRCI) scoring system. Medication compliance was evaluated utilizing MARS – 10 (Medication Adherence Report Scale – 10) questionnaire. Sociodemographic information, clinical measurements (such as HBA1C,Fasting blood sugar, Postprandial blood sugar and lipid profile ), duration of illness, existing health conditions and treatment expenses were documented. A Statistical analysis was conducted to identify the relationship between MRCI scores and levels of medication adherence. Results: The research included 122 individuals with Cardiovascular disease and Type 2 Diabetes Mellitus. According to Spearman’s correlation analysis, the Medication Regimen Complexity Index (MRCI) was not strongly correlated with medication adherence (MARS – 10). There was no statistically significant correlation between adherence and sociodemographic variables like education, income and the cost of therapy treatment (p>0.0001).When looking at clinical factors, the number of drugs and co-morbidities did not show a significant link to adherence, but the length of CVD and blood glucose levels showed only a little connection. In general, there was no discernible correlation between how complicated a treatment plan was and how well patients followed it. Conclusion: The influence of the Medication Regimen Complexity Index (MRCI) on medication adherence was evaluated in this observational study involving 122 individuals with T2DM and CVD. The results indicated no correlation between adherence and MRCI (p = 0.040, p = 0.666). With the exception of minor associations with blood glucose levels and the length of Cardiovascular disease, the majority of sociodemographic and clinical variables were not significantly linked to adherence. In general, the findings indicate that in this population, adherence to medication may be more influenced by variables other than the regimen’s complexity.