It is true that when blood sugar falls to low levels (a condition called hypoglycaemia) people may feel sweaty, giddy, anxious, hungry, angry and tremulous. However it is impossible to accurately guess when sugar levels have risen on a daily basis without testing. There are no reliable symptoms to indicate rising blood sugar levels. Both blood sugar highs and lows can display identical symptoms like severe tiredness. This makes it difficult to know if blood sugars are high or low. Therefore, it is important to test blood glucose levels rather than rely on any feelings of highs and lows..These are the following ways to test blood glucose levels:.Random blood glucose test requires a blood sample to be taken. Regardless of when you last ate, a reading of 200mg/dL or higher would indicate that you have Diabetes. However, this is not a good diagnostic test..Fasting blood glucose test requires a blood sample to be taken after an 8-12 hour overnight fast. A fasting blood sugar level between 100-125 mg/dL indicates prediabetes, whereas levels >125 mg/dL indicates that you have Diabetes..Postprandial blood glucose test measures blood glucose levels following a meal containing a set amount of carbohydrate. A 2-hour postprandial blood glucose test measures blood glucose exactly 2 hours after eating a meal, timed from the start of the meal. By this point blood sugar has usually gone back down in healthy people, but it may still be elevated in people with Diabetes..HbA1c or glycated haemoglobin is a test that measures average plasma glucose concentration. HbA1c test (glycated haemoglobin test) is done to assess your blood sugar control over the previous two or three months..The advantage of this test is that it does not require fasting and can be done anytime during the day. A result of 5.7- 6.4 per cent denotes Pre-Diabetes and a result of 6.5 per cent or higher indicates Diabetes..Glucometers offer at home convenience of home blood tests. A glucometer at home is very useful. Whenever you get symptom, that you wish to attribute to high or low sugar, do an immediate glucometer based estimation and that will give a quick approximate guide to your levels..Continuous Glucose Monitoring System or CGMS is a device that records glucose levels throughout the day and night. It provides up to 288 glucose readings in 24 hours. The system is used to measure average blood glucose for up to 6 days..It involves a tiny, sterile, flexible electrode being inserted just under the skin. A tiny pager-like device shows you the readings every few minutes. These readings give a more accurate picture of how your blood glucose level changes throughout the day, warning you of highs and lows almost immediately.