You have a wide choice that ranges from walking, aqua training, cycling, and weight training with small weights.
However, I will focus on yoga and meditation that I have found useful in many medical conditions.
A systematic review of articles and studies on the health impact of yoga shows that its practice helps in weight control, blood pressure, blood lipids, and blood sugar reduction. (Yang, K., 2007; Youngwanichsetha, S. et al., 2014)
Yoga and standard physical training exercises both positively impact 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)
In addition to breathing exercises, eight forms of physical activities – (Yoga asana)- have been observed to benefit diabetic patients. These exercises were practiced each day for 45 minutes, followed by relaxation exercises like Shavasana (Deadman pose) and Makrasana (Crocodile pose).
The yoga asanas practiced were Dhanurasana (Bow Pose), and Ardha matsayendrasana (half spinal twist) helped control diabetes optimally. Halasana (plow pose), Vajrasana (sitting posture with feet under your hips, Bhujangasana (Cobra pose), Naukasana (boat pose) were effective.
Yoga mudra (sitting with one finger of the hand touching the thumb) and Shalabasana (locust pose) adversely affected people with diabetes and worsened their diabetes status. It is an interesting observation and indicates that the nature of exercise is also vital in diabetes management. Individually Dhanurasana (Bow pose) was most effective in diabetes control. Yoga was useful for people with diabetes of all ages. (Sahay, B.K., 2007)
Yoga (pranayama and Yoga asana) and stress management education positively impacted diabetes patients. (Bijlani, R.L. et al., 2005)
It is best to begin yoga, pranayama, and meditation under the supervision of a yoga and meditation specialist.