Compliance in implementing a healthy diet and lifestyle is the main key in controlling blood sugar levels in people with diabetes mellitus. If it is not controlled, it will cause various diseases that will be caused by impaired eyesight, cataracts, heart problems, impaired kidney function, sexual impotence, difficult to heal a wound, or even rot/gangrene, occurrence of lung infections, disorders of blood vessels and strokes. The purpose of this study is to determine what factors influence diet adherence in people with diabetes mellitus for the occurrence of complications.This research uses mixed methods. This research uses accidental sampling and obtained quantitative data of 77 respondents to see the relationship between diet adherence with the occurrence of complications, and after that qualitative data, of 10 respondents were conducted by interview knowing what factors influence diet adherence.Quantitative statistical test results p-value = 0.002 <α = 0.05, which means there is a relationship between diet adherence with the occurrence of complications. While the results of qualitative data obtained three themes, namely lack of dietary knowledge, no family support, and difficulty in complying.Adherence to the diet in people with diabetes mellitus is very important to prevent complications; therefore the health team needs to always provide knowledge on how to diet properly, and families are expected always to support the diet so that motivation arises to carry out the diet in order to avoid complications seriously.