A Gaithersburg man was killed early Sunday morning when the pickup truck he was driving veered off Route 108 and struck a tree.

Montgomery County police says an off-duty officer contacted police after noticing the pickup, driven by Antonio Ayala, 49, driving erratically around 1 a.m. Another officer arrived at Route 108 and Hawkins Creamery Road in an effort to get the truck to stop, but the vehicle left the eastbound lane of Route 108 and struck a tree. Ayala died at the scene.

Family members told police Ayala was a diabetic and used insulin and was last seen Saturday around 6 p.m. when he left his house for groceries. Police are continuing their investigation. Anyone with any information is asked to call 240-773-6620.