ALS is difficult to diagnose because the initial symptoms can be very similar to other diseases, according to the ALS Society of Canada. He noted it can take upwards of 18 months from the onset of symptoms to come to a diagnosis. "I'm sorry to say this: Family physicians should never be making a diagnosis of ALS because it's a diagnosis of expertise and a diagnosis of exclusion," Zinman said. "It's very hard to give that diagnosis. It's complicated." https://www.cbc.ca/news/canada/manitoba/als-misdiagnosis-diabetes-winnipeg-1.7062773