In just about every home there is a Glass Sliding Door, at least in Florida. They can be easily opened even locked by picking up the door off the track enough to release it from the catch. I didn’t believe this until a Door/Window installer showed me.
The easiest way is to use a pole to secure it but what if you have a Door that opens from both sides or is a multi-pane door?
The simple answer is a Lock Pin. They’re dirt cheap and can easily be installed as long as you have the correct Drill bit.
If you have an Alarm System don’t think a simple Glass Break sensor will work. A lot of these type of Doors uses a type of glass similar to a Car’s Windshield. I found this out when I was 19 and hit a rock with the lawn mower and it took out the door. Cracked the hell out of the outer pane but not enough to shatter it. The best thing to do is use a typical Door Sensor. I wouldn’t worry about a Motion Detector because bright light can trip it so if you have outdoor lighting it could set it off. I wouldn’t advise to use a shock sensor either. The door is flimsy so a good gust of wind could shake it.
If you have a vinyl door it should work but over time it could wallow out the hole or crack the frame. There probably is other types of Pin Locks that will work for it.
Another Door type is where two panes open in the center. I would use something like this.
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