Vinegar supplements are not dangerous to a diabetic and can, in fact, help to manage blood sugar, explains Everyday Health. Two tablespoons of vinegar preceding a meal or vinegar worked into recipes can help to keep blood sugar from spiking dangerously after eating.
Apple cider vinegar, made from apples, helps to prolong the breakdown of food into sugar so that it doesn't absorb into the blood all at once, states WebMD. This slower absorption helps to keep blood sugar from spiking after meals; however, more research is necessary to determine the effectiveness of apple cider vinegar for managing diabetes.
Vinegar supplements can be dangerous if taken in large amounts. Consumption of more than 1 cup of vinegar per day for a long period of time may be lead to low potassium levels, says WebMD. The effects of vinegar supplements on pregnant and breastfeeding women are unknown. Apple cider vinegar reacts with insulin, digoxin and water pills. Because both apple cider vinegar and insulin decrease potassium levels in the body, individuals should only ingest small amounts of apple cider vinegar in conjunction with insulin shots to keep potassium from dropping to dangerously low levels. Diabetics who want to use apple cider vinegar supplements need to consult a doctor for proper dosing.