I understand your concerns about your mothers diabetes. But one thing you need to remember that post prandialsugar level is not a true indicator of how good you sugar control is. For example have a light breakfast containing only oats and get PP test done- sugar will be low , whereas get it repeated after having something like kichdi or something containing rice, it will be high. Hence you should never rely on just one fasting and pp test to make adjustments to the medications she is having. I would suggest you get it repeated and make sure she eats a normal BF which she takes on most days and also get her HBA1C blood test done at the same time.