Purpose The purpose of this umbrella review was to synthesize the evidence from published systematic reviews on the effectiveness of text message programs for adults with type 2 diabetes (T2DM) on glycemic management (A1C), self-management, and other clinical outcomes. The effect of directionality of the program was also explored. Methods A systematic search was conducted using multiple databases. Inclusion criteria were systematic review of text message programs for adults with T2DM, evaluated A1C, and English language. Quality assessment was completed using AMSTAR-2 guidelines. Data were extracted by multiple coders, and results were synthesized. Results The final sample included 9 systematic reviews published between 2011 and 2019, with 72 unique international studies. Text message programs focused on diabetes self-management and reducing health risks through educational and motivational content with some providing personalized feedback. A meta-analysis of program effect on A1C was conducted in 5 reviews with a pooled difference in A1C from −0.38% to −0.8%. Adults with T2DM of shorter duration and lower A1C had better treatment effects. Evidence on unidirectional versus bidirectional programs is conflicting; however, both improve outcomes. Evidence of text message programs targeting medication engagement was inconclusive. Some programs improved blood pressure, lipids, self-management, self-efficacy, and health behaviors. High satisfaction and an average of 9.6% to 18.7% attrition was reported. Conclusions Text messaging programs can improve T2DM outcomes, are a highly accessible mode of communication, are relatively inexpensive, and are an underutilized adjunct to clinical care.