Diet interventions have suggested an association between plant-based diets and improvements in psychological well-being, quality of life and glycated hemoglobin (HbA1c) control in populations with diabetes. The aims of this review are to systematically analyze the available literature on plant-based diet interventions targeting diabetes in adults and to clearly define the benefits on well-being of such interventions. This is a systematic review of controlled trials. A computerized systematic literature search was conducted in the following electronic databases: Allied and Complementary Medicine, Cochrane Central Register of Controlled Trials, Cumulative Index to Nursing and Allied Health Literature, E-Journals, Excerpta Medica Database, MEDLINE, Health Management Information Consortium, PsycARTICLES, PsycINFO, PubMed, SocINDEX and Web of Science. The search strategy retrieved 1240 articles, of which 11 met the inclusion criteria (n=433; mean sample age 54.8 years). Plant-based diets were associated with significant improvement in emotional well-being, physical well-being, depression, quality of life, general health, HbA1c levels, weight, total cholesterol and low-density lipoprotein cholesterol, compared with several diabetic associations’ official guidelines and other comparator diets. Plant-based diets can significantly improve psychological health, quality of life, HbA1c levels and weight and therefore the management of diabetes.