My glucose - serum/plasma (random/casual) is 128. sample given after 3.5 hours of eating. do i have diabetes?

No: no it does not mean anything that a kind or normal sugar after eating. if you are concerned if you have diabetes or not,you can ask your doctor to do a fasting blood sugar and a test called Hg AIc which give you your average blood sugar for the last two weeks. good luck. i hope that answer your question, and your concern.

Maybe : It would certainly help to see your height and weight and thus BMI here, definitely input that for a Prime Consult on Healthtap. In the US our professional guidelines hold that a blood sugar between 100 and 140 is in the range of "prediabetes" . There is a continuum from normal 2 Prediabetes 2 diabetes. User error/device error possible especially if normal BMI exercise and diet.