Diabetes mellitus refers to a group of diseases that affect how the body uses blood sugar (glucose). Glucose is an important source of energy for the cells that make up the muscles and tissues. It's also the brain's main source of fuel. The main cause of diabetes varies by type. As a noun, DM stands for a private message sent on social media, such as on Instagram or Twitter, to one person or a group. In most instances when people ask you to DM them, they're referring to a Direct Message. A direct message is a private communication between social media users and is sometimes referred to as a private message or PM. When you send a direct message, only you and the recipient can see the content. The meaning of DM is a private message sent on social media to a specific individual or group. How to use DM in a sentence. Willkommen im Onlineshop von dm – Deinem Drogeriemarkt. DM stands for Direct Message. A DM is a private message between two people, usually on a social media website or app. Although it originally referred to private messages sent on Twitter, DMs now refer to private conversations on almost every social media platform. The Oregon Driver and Motor Vehicles division of ODOT is where you go to get a driver license, ID card, register your vehicle, and more.