Locks for sliding glass doors can break from time to time. When that happens it is highly recommended to get such issue resolved sooner than later. Sliding glass doors tend to be facing the back part of the home which makes them extremely vulnerable for break-ins. The entries that cannot be seen from the street allow the burglars to enter your home without worrying about being seen by a neighbor or people passing by it.
It is always important to know the state of your sliding door lock and make sure that it is latching securely by trying to forcefully shake the door back and forth and see if it breaks open. Many times if the latch and keeper are not properly aligned the locked door could easily be forced open just by shaking or pulling it aggressively. If this is the case, an experienced locksmith should know how to align the parts properly.
If you are looking to make your sliding door more secure you can always install a security bar or install a motion activated outdoor light above it. An alarm can also be a good deterrent as long as you let the burglar know it’s there by warning him with a visible sticker.
Most sliding glass door locks tend to come without a keyed cylinder, but most come with the option of adding one. The only situation that would make sense to do that is if someone needs to unlock the home from the sliding glass door side. If that is the case, you can always call a professional locksmith to install a keyed cylinder or replace the entire lock.