Kombucha can be suitable for diabetics, even though it is made from a sweet tea base. What happens is the SCOBY (a culture of bacteria and yeast) feed off of the sugars and converts them to probiotics, organic acids, antioxidants, vitamins, carbon dioxide and a tiny bit of alcohol as a by-product of fermentation. So what is left is a drink with low sugar content. It is better / safer to consume raw / unflavoured Kombucha rather than the ones where fruits and herbs are added for flavor because of the fruit sugars even though it is left to ferment further.
Because of complications, we would advise to start off very slowly at first like a small cup of 50ml & dilute with water to see how the body feels. If the body reacts well, consumption can gradually be increased. If distress symptoms appear (e.g. fever, body aches, flare ups), reduce consumption for a while before starting back up again. Please consult with your GP / doctor before consuming to make sure everything it is safe before embarking on Kombucha.
It should be noted that Kombucha is not a cure for diabetes – other aspects of health such as diet, sleep exercise etc. plays a part as well. But Kombucha is worth considering due to its probiotic and antioxidative benefits that could regulate pancreatic cells and help the body manage insulin / blood sugar levels. Its also definitely a better alternative to sodas or fruit juices.