There ARE appliances that can warn you of low blood glucose levels, my friend. They are called CGMS (Continuous Glucose Monitoring System). They are normally used with an insulin pump, so if you're injecting insulin I'm afraid you'll need to check out with your diabetes support team ... doctor/diabetes specialist nurse/certified diabetes educator ... to see if there's a way that they can be used that way.
The lack of warning that you're getting when your blood sugar (glucose) levels fall is called hypoglycemia unawareness. You need to inform your diabetes support team about this. They MAY get you to run your blood sugar levels higher for a short time to see if your awareness improves. Sadly, this doesn't work for everyone. If you've developed a complication called diabetic autonomic neuropathy, this will affect how your body responds to internal signals.
What I can tell you is that CGMS is very expensive. You need to wear an 'implant' that needs to be changed every 3 or 4 days. The bad news is, if your blood sugar level drops rapidly, you still MAY not get sufficient warning to do anything about it. (I wasn't getting the warning from my pump until such time as I had lost consciousness, even though I'd set my pump to alarm once my blood sugar level had dropped to 5.5 mmol/l [99 mg/dL]. The reason behind this is that the CGMS takes readings from the interstitial fluid ... fluid between your body's cells ... rather than directly from blood. This causes a delay in the results obtained.)
I'd urge you to speak with your diabetes support team, my friend, to see what they suggest.
I wish you well.