Yes. Unfortunately, people who have heart disease, cancer, diabetes, hypothyroidism, eating disorders, irritable bowel syndrome/IBS , and extreme fatigue, as well as people who are underweight, recovering from surgery, or pregnant/lactating, should avoid aggressive fasting detoxification programs.
Hypothyroidism causes many metabolic abnormalities as well as multiple clinical symptoms. Some studies suggest that blood sugar may be affected in hypothyroidism and levels may increase.
All juices cleanses -due to their nature- are high in natural sugar. This is what you and your doctor should take into consideration. Just proceed with caution and make sure you get the ok from your doctor.