Blood sugars

What medication are you on?

Did you have any hypo symptoms to warn you you were low? Do you know to correct with fast acting glucose?

And did you feel strange at all when your monitor was showing 1.6?

What sort of levels do you normally have? Are you often below 4?

Metformin is not going to cause hypoglycemia (or at least to those levels). My guess is that the meter malfunctioned and caused a false reading.

Even if you were taking a sulfonylurea (Gliclazide) it would still be incredibly unlikely for it to cause levels that low. Heck, it would even take an incredibly rare and severe case of reactive hypoglycemia to actually reach levels that low.

If it were me, I'd chalk it up to a technical glitch.

I've had low results like that in the past it's always been false readings, if it happens again retest.