Good morning,
Avon and Somerset Police have made the following suggestions for added security on patio doors where over 80% of house burglaries take place, a simple remedy is to fit a length of wood that lies on the floor to prevent the sliding door from moving, (the inner door that slides across not the outer one), you can also fit a lock “Padlock” or similar device between the handles to strengthen the locking mechanism, or for about £5 each fit a glass shock alarm that makes burglars think that an alarm will sound sound if the glass is smashed or the lock/handle is attacked forcefully.
Have a nice day.
Colin