There are scientific studies that support the positive role of yoga in diabetes.
A systematic review of articles and studies on the health impact of Yoga shows that its’ practice helps in weight control, reduction of blood pressure, blood lipids, and blood sugar. (Yang, K., 2007; Youngwanichsetha, S. et al., 2014)
Yoga and standard physical training exercises both have a positive impact on individuals who have diabetes. It helps reduce oxidative stress and bring about improvements in antioxidant profiles. (Gordon, L.A., et al., 2008)
Diabetic individuals who performed pranayama felt a sense of well-being in 7 to 10 days of practice. Demand for insulin, other diabetes control medicine dropped. In this trial, four types of pranayama were practiced for 30 minutes, followed by 10 minutes of resting yoga posture called Shavasana (a dead person pose posture). (Sahay, B.K., 2007)
Even though I have quoted the above studies supporting yoga in diabetes management, I would like to caution that these studies are not well cited. Still, it is well accepted that exercise, in general, does help diabetes patients. Claims of miraculous cures by yoga, to my mind, are dangerous.
Natural Solutions for Diabetes, cancer, and obesity – a tri-series