Diabetes mellitus is a group of metabolic disorders characterized by prolonged elevation of blood glucose levels, inducing numerous complications such as retinopathy, kidney disease, heart disease and stroke. β cells in the pancreatic islets are responsible for regulating blood glucose levels through secretion of insulin, which stimulates cells in the body to take up glucose from the blood. This process is disrupted in diabetes patients, who either suffer from autoimmune induced β cell death (type 1 diabetes, insulin deficiency) or fail to respond to insulin signaling (type 2 diabetes, insulin resistance). In this dissertation, I will discuss interesting findings stemming from this study, which suggests that the donor cell type of origin influences the molecular and functional properties of reprogrammed cells. Reprogramming approaches developed in this dissertation offer alternative treatment strategies for type 1 diabetes patients and the experimental observations made through using different cell types and reprogramming factors for cell fate conversion shed light on the mechanisms of the direct lineage reprogramming process.