Diabetics. Like other honeys, manuka honey contains a high amount of sugar, about 80% thus, it will increase blood sugar levels after consumption. As such people with diabetes or prediabetes are advised to stay away from manuka sugar. Also, some people are allergic to manuka honey, especially those allergic to bees. So, in case you get any allergic reactions after consuming manuka honey, it is advised to stay away. Babies. Generally, parents are not advised to give their babies any honey at all, so manuka honey should not be given to babies.