The reviewed research evaluated how walking at different times affected the blood glucose after a meals (Dipietro L,et al. 2013).
The participants were 60 years or older inactive individuals with elevated fasting blood glucose levels between 105 and 125 mg/dl. The exercise protocols consisted of either 15 minutes of walking after meals, or 45 minutes of sustained walking at 10:30 AM or 4:30 PM. The walking was done on a treadmill, and all the participants walked at the same intensity.
Both the 45 minutes morning walk and the 15 minutes walk after a meal significantly improved 24 hour glycemic control when compared to not walking. Walking 15 minutes after a meal was however significantly more effective in reducing the blood glucose 3 hours after dinner than walking 45 minutes in the morning or 45 minutes in the afternoon.
You should exercise after you eat if you want to use exercise as a tool to lower blood glucose. You will get greater benefits from exercise if you exercise more than once per day, even if it is just for a few minutes.