There's no other information provided, but the question certainly seems sincere, and I think an answer should be sent; so here's my reply:
I understand that both your mother and father have diabetes, but I am missing a lot of information that would help analyze the situation in more detail. Blood glucose values of 140-160 mg/dl are high if measured before eating breakfast, but may be perfectly okay if checked soon after a meal. Another test, the A1C, would be a big help to figure out how their diabetes is doing. I will give you some general advice, and hope that your parents appreciate your willingness to help them.
First, do you live with them, or elsewhere? If you live with them, I would encourage you to go with either or both of them the next time they see their diabetes physician or nurse, and ask what you might be able to do to assist. For instance, helping your parents with choosing appropriate foods to purchase, or reminding them to do fingerstick blood sugar tests, or to take their medications on time, might be very helpful. Also, if either of them are on insulin therapy, learn more about how to recognize and treat hypoglycemia. And you should request information on how to help if either of them have an acute illness (such as a virus). Be sure that someone is checking their eyes, feet, and heart for any complications that could be detected early. If they are smokers, they should be encouraged to quit. If they like learning more about diabetes, there are many websites they could visit, including this one.
There's also tons of information that might help at a US government website, http://diabetes.niddk.nih.gov/. If they aren't comfortable with computers, you could volunteer to print out information they might want to review.
If you don't live with them, but live nearby, then the same suggestions apply.
If you live far away, in addition to the above thoughts, be sure to check with them to be sure they keep in regular touch with their physician, and encourage them to keep you informed on how things are going with their health.
If they have other medical problems besides diabetes, ask the physicians what other recommendations they can make for you to assist.
By the way, if they are uncomfortable with their present physician, see if you can help them find another physician to treat their diabetes.
Finally, as both your parents have diabetes, you are at risk of also becoming diabetic. You should ask your physician or a dietitian about what foods to eat and which to avoid; you should remain physically active as much as possible, and have your blood glucose level or A1C test done on an occasional basis to see how you are doing. If you are overweight, losing weight should help decrease your risk.
Best wishes to you and your parents!