What is involved in a Blood sugar test?

Blood sugar test measures the level of glucose in your blood. Glucose is the main source of energy for your cells. Your blood sugar levels can be affected by many factors, including what you eat, how much you exercise, and certain medical conditions.

Fasting blood sugar test

- Don’t eat or drink anything (except water) for at least 8-12 hours before the test. Your doctor will tell you how long to fast.

- A blood sample will be drawn from a vein in your arm.

- The sample is sent to a lab where it is analysed.

Random plasma glucose (RPG)

- You can eat and drink normally before the test.

- A blood sample will be drawn from a vein in your arm.

- The lab performs the test.

Oral glucose tolerance test (OGTT)

- Don’t eat or drink anything (except water) for at least 8-12 hours before the test. Your doctor will tell you how long to fast.

- A blood sample is drawn from a vein in your arm to get a baseline measurement.

- You will then be given a sugary drink to drink.

- Blood samples will be drawn again at timed intervals after you drink the sugary drink (usually every 30 minutes or hour) for the next 2-3 hours.

You will be advised not to smoke or exercise strenuously for at least 30 minutes before the blood test.

Results

- The results of a fasting blood sugar test are usually reported in milligrams per deciliter (mg/dL).

- Normal fasting blood sugar level is less than 100 mg/dL (5.6 mmol/L).

- Impaired fasting glucose (IFG) is a fasting blood sugar level between 100 and 125 mg/dL (5.6–6.9 mmol/L).

- A blood sugar level of 126 mg/dL or higher (7.0 mmol/L) on two separate fasting tests may indicate diabetes.

The results of a random plasma glucose (RPG) test may be reported as mg/dL or millimoles per liter (mmol/L).

- A random blood sugar level less than 140 mg/dL (< 7.8 mmol/L) is usually considered normal.

- A random blood sugar level of 200 mg/dL (11.1 mmol/L) or higher on two separate tests may indicate diabetes.

The results of an oral glucose tolerance test are usually reported as a series of blood sugar levels drawn at timed intervals after you drink a sugary drink.

- Normal glucose tolerance is diagnosed if your blood sugar level is less than 140 mg/dL (7.8 mmol/L) 2 hours after drinking the sugary drink.

- Impaired glucose tolerance (IGT) is diagnosed if your blood sugar level is between 140 and 199 mg/dL (7.8–11 mmol/L) 2 hours after drinking the sugary drink.

- Diabetes is diagnosed if your blood sugar level is 200 mg/dL (11.1 mmol/L) or higher on two separate oral glucose tolerance tests.

Your doctor will interpret your blood sugar test results based on your individual situation.