The Committee of Clinical Practice Guidelines of the Korean Diabetes Association (KDA) updated the previous clinical practice guidelines for Korean adults with diabetes and prediabetes and published the seventh edition in May 2021. We performed a comprehensive systematic review of recent clinical trials and evidence that could be applicable in real-world practice and was suitable for the Korean population. The guidelines are intended for use at sites across the country by all healthcare providers (including physicians, diabetes experts, and certified diabetes educators) who treat diabetes. The recommendations for screening diabetes and antihyperglycemic agents have been revised and updated. Continuous glucose monitoring with insulin pump use and screening and treatment for non-alcoholic fatty liver disease (NAFLD) in the type 2 diabetes sections were newly developed. The KDA recommends active vaccination for COVID-19 in patients with diabetes during the pandemic. An abridgement that contains practical information for patient education and systematic management in the clinic was published separately.