Question: What is the difference between the number of married patients and the number of single patients with diabetes?
SQL: SELECT SUM(CASE WHEN T2.marital = 'M' THEN 1 ELSE 0 END) - SUM(CASE WHEN T2.marital = 'S' THEN 1 ELSE 0 END) FROM conditions AS T1 INNER JOIN patients AS T2 ON T1.PATIENT = T2.patient WHERE T1.DESCRIPTION = 'Diabetes'