In the United States there is a test, the Gad65 test which is a blood test. If you are symptomatic and have an elevated gad65, that is the disagosis. However a gad65 can also be positive if the patient has diabetes so the levels would need to be looked at, however SPS and diabetes coincide more often than not. Patients don't always test positive and are diagnosed based on their symptoms. Spasms, weakness, falls and many more.