Probably the most well-known health benefit of cinnamon is for blood sugar disorders. And this is for good reason. There is now a rather substantial body of clinical and preclinical research showing that it may help to improve the condition of both type 2 and type 1 diabetics in the following ways:

Type 2 diabetics: Improve fasting blood sugar,[ii] reduce glycated hemoglobin (A1C) and blood pressure,[iii] increase glucose optimization in a manner similar to metformin,[iv] [v]improve insulin signaling and sensitivity,[vi] [vii] and improve blood lipid profiles.[viii]

Type 1 diabetics: Protect against hypertension,[ix] protect against diabetes-associated kidney damage,[x] suppress post-meal blood sugar elevations,[xi] and contribute to ongoing reduction in blood sugar.[xii]
Infections

While there is extant folk medical lore indicating that honey mixed with cinnamon can help relieve a sore throat, or fight off infection, few realize it has been confirmed to have extensive anti-infective properties against a wide range of bacteria, viruses and fungi.

It makes sense that cinnamon bark would protect against infection, as one of the major biological functions of plant bark is defense against predation (i.e. infection).