DTM

In sport:

Deutsche Tourenwagen Masters, a motor-racing series staged annually in Germany since 2000
Deutsche Tourenwagen Meisterschaft, a motor-racing championship staged in Germany from 1984 to 1995

In computing:

Deterministic Turing machine, an abstract symbol-manipulating device that was first described in 1936 by Alan Turing
Digital terrain model, a digital representation of ground-surface topography or terrain
Discrete multitone modulation, an ADSL modulation method
Driver Test Manager, a test-automation framework provided by Microsoft as a part of Windows Driver Kit (WDK)
Dual Transfer Mode, supporting simultaneous voice and packet data in a GSM network
Dynamic synchronous Transfer Mode, a networking technology

In process control/automation:

A Device Type Manager (DTM) is part of the Field Device Tool (FDT) standard that is a software component for a device that contains the device-specific data, functions and logic elements. DTMs can reach from a simple graphical user interface for setting device parameters up to a highly sophisticated application that, for example, can perform complex calculations for diagnostics and maintenance purposes or can implement arbitrarily complex business logics for device calibration.

In media:

Dennis the Menace (disambiguation), original comics as well as TV series, films and video games based on them
Detroit Techno Militia, a collective of techno DJs and Musicians in Michigan.
DTM stands for desktop music, an English term originating from Japan, roughly meaning Computer Music.

In demography:

Demographic transition model, a model used to represent the changes in birth- and death-rates of a country

In certification:

In transportation: