Preliminary autopsy results suggest Mark Santos was not hypoglycemic when he drove his semi-trailer the wrong way down a busy Edmonton freeway and off an overpass.

"We did do a preliminary kind of a test ... almost like what you'd call a field test to determine what, perhaps if we could get some idea what his blood sugars were," Dennis Caufield, a senior medical examiner, explained Thursday.

Early autopsy results suggest that a diabetic reaction was not behind Monday's fiery semi-trailer crash.
(CBC)

"That initial field test suggested his blood sugars appeared to be relatively normal." 

Santos, 25, drove his truck erratically for more than 15 kilometres on Monday before going the wrong way down Yellowhead Trail, hitting a guardrail, and rolling off the overpass. The fuel tanks on his semi exploded as the vehicle smashed onto the railways tracks below.

He was pronounced dead at the scene.

Santos's family said earlier in the week that Santos had Type 1 diabetes and sometimes suffered severe hypoglycemic reactions that caused seizures and blackouts.

Caufield stressed that further tests are still needed, as the initial tests do not provide examiners with specific numbers in terms of blood sugar levels, just whether the levels are low, normal or high. He said the current findings could not be used in court.

Caufield said he will have a better idea on whether Santos had low blood sugar levels when more detailed toxicology results are released in three to four months. Those tests will also look for drugs and alcohol, as well as carbon monoxide to see whether the fire played a role in the death.

Police are still investigating the crash.