This is a systematic review of the factors and reasons associated with follow-up non-attendance (FUNA) in patients with Type 2 diabetes mellitus and hypertension in an outpatient setting. We performed a systematic literature search using electronic databases and related keywords with the PRISMA-P checklist, focusing on the factors, types of studies and number of studies that showed a positive, negative or neutral association with FUNA. Data was presented in three categories: patient, disease and medication, and healthcare provider factors. In total, 4,822 articles were reviewed. Among the 24 articles that were relevant to the stated objective, 83 factors were found to be associated with FUNA. A target-board model for FUNA was presented for clinicians to better understand the various aspects contributing to and implications involved in FUNA. Greater awareness and understanding of the multifactorial nature of FUNA and taking a multifaceted approach are important to effectively reduce this problem.