A level of 12mmol/L, which converts to about 216 mg/dl (multiply by 18), is abnormal for a postprandial glucose level. You should speak to your endocrinologist
regarding your management and follow up.
Diabetes Mellitus (DM) is a condition in which glucose is not metabolized correctly and results in hyperglycemia (high blood sugar levels). The oral glucose tolerance test (OGTT) is a standardized way of evaluating postprandial glucose measurements. In this test, you are given glucose orally and then your blood sugar is checked two hours later. A normal value would be a glucose level less than 140mg/dL. The term impaired glucose tolerance is given if the 2 hours level is between 140 and 200 mg/dL. If the level is above 200mg/dL and you have symptoms of diabetes, then you are diagnosed with DM. While it is common for patients with diabetes to have a 2hr postprandial glucose of over 200mg/dL on diagnosis, the hope is that with proper treatment, your glucose level can decrease below to 200, reaching closer to 140mg/dL. It has been shown that a 2hr postprandial glucose of greater than 140mg/dL resulted in a cardiovascular risk factor. Some organizations recommend keeping postprandial glucose at less than 140mg/dL and others recommend a level less than 180-200mg/dL.
It is important to keep in mind that this is only one measurement and likely not enough to make a proper assessment on your diabetes control. Your physician may obtain a Hemoglobin A1C which is a reflection of your average blood glucose levels over the last 2-3 months. You should follow up with your endocrinologist to go over your glucose measurements and discuss possible changes to your management if needed.