Hello, Thanks for the query. The blood glucose levels fasting 77 mg is normal. However, 171 mg after lunch if that is after 2 hours, then does signify presence of gestational diabetes. My suggestion is get a Oral Glucose Tolerance Test done immediately. If the test values are above 180 mg after 1 hour, & 153 mg after 2 hours, then it is confirmed as gestational diabetes. This has to be immediately controlled first with dietary control. If that does not work, then Insulin injections . It is absolutely essential to maintain blood glucose between 90 to 120 mg all through out the day. For expected normal outcome of pregnancy and for the health of the fetus this is necessary. Increased glucose level can lead to a bigger fetus (macrosomia) and difficulty in delivery. So please get the necessary test immediately. Then follow doctors instructions meticulously. Thanks.