While it did not topple the Roman Empire, the plague insured the Dark Ages began very dark indeed.
Very interesting book about the time period, and the possible causes of the Dark Ages. Volcano - Weather - Famine - Plague. All basically inter-linked, but basically starting with a volcano.
The term Dark Ages is an invention of Enlightenment atheists. The Dark Ages weren’t dark at all. A lot was happening, just outside the purview of the Roman State.