  So far, no systematic long-term blazar monitoring programs and detailed
variability studies exist at sub-mm wavelengths. Here, we present a new sub-mm
blazar monitoring program using the APEX 12-m telescope. A sample of about 40
gamma-ray blazars has been monitored since 2007/2008 with the LABOCA bolometer
camera at 345 GHz. First light curves, preliminary variability results and a
first comparison with the longer cm/mm bands (F-GAMMA program) are presented,
demonstrating the extreme variability characteristics of blazars at such short
wavelengths.
