There have been some reports connecting low blood sugar and bad breath. This has been particularly noted in diabetic individuals. Ketoacidosis is a condition the body enters when it burns fat instead of sugar (glucose) for energy. This happens to diabetics when they do not have enough insulin to metabolize glucose or to people on very carbohydrate restricted diets, such as the Atkins Diet.
The low sugar condition is associated with an unpleasant, fruity, metallic taste in the mouth and scent to the breath. The only complete cure for this is to raise the blood glucose through diet or other methods. Breath mints and mouthwashes can help temporarily; however they will not cure the problem, only mask the symptoms. Fortunately for diabetics, many of these products are available sugar-free. Diabetics who are in a state of ketoacidosis characterized by bad breath should seek medical care immediately, as this can quickly become life-threatening.
Dry mouth is another symptom associated with low blood sugar that will contribute to bad breath. Increasing water intake and reducing other beverages may help alleviate this issue. There are also prescriptions that will help keep the mouth moist which prevents the growth of bacteria that create halitosis. Sugar-free gums and mints can also help with dry mouth on a temporary basis. Ingesting a lot of sugary fluids will likely make the problem worse, though.
Halitosis is just one of many symptoms that can indicate low blood glucose. It is a very noticeable one and can serve a positive function by alerting the individual or their loved ones that blood sugar is low so steps can be taken to raise it. It is one of the many challenges that face people with diabetes and can usually be managed with diet and home care, but can be an unfortunate fact of life that must be lived with.