Cinnamon is found in many types of foods. In North American, it's primarily found in sweets. It certainly isn't uncommon. However, studies have not conclusively shown that cinnamon can be part of an effective treatment for diabetes, or that it lowers or can control blood glucose levels.
At the same time, including cinnamon in moderation in your diet doesn't appear to be unsafe. There is a risk that no one really knows how much cinnamon is safe to consume (and besides, some will argue, there are other effective medications that are known to treat type 2 diabetes). In the study mentioned above, participants were given 1 gram, 3 grams, or 6 grams of cinnamon per day.
Lifestyle changes are highly important as well -- no single factor will control diabetes. Some people report that cinnamon has helped. If you decide you want to try taking cinnamon as a diabetes treatment, monitor your blood sugar levels closely to make sure they remain under control.
Of course, this isn't an excuse to excessively consume cinnamon buns or other sweets. These types of foods typically contain large amounts of carbohydrates that will raise blood sugar levels far more than cinnamon will lower them! Plus don't forget the extra calories which can result in weight gain, something that people with diabetes need to control.
You might decide you'd like to try cinnamon as part of your diet to see if it has any effect on your blood glucose control. Always discuss it first with your doctor, whether you'll be adding the spice in larger quantities to your foods, or you want to order cinnamon supplements. Supplements can have sometimes compromise the effectiveness of certain medications, including medications you may be taking for other health conditions. Cinnamon might also interact with other supplements or meds, and it could be unsafe for people with liver problems. Be sure to continue to monitor your blood sugar if you start to include cinnamon as part of your diet. Notify your doctor if your blood sugar readings are different than usual.