Normal fasting glucose range: 70 to 99 mg/dL (3.9 to 5.5mmol/L)

Prediabetes: 99 to 126 mg/dL (5.5mmol/L to 7.0mmol/L)

Diabetes: Higher than 126 mg/dL (7.0mmol/L) in multiple subsequent tests

Glucose is a simple sugar or monosaccharide which is the main source of energy for all the cells of the body, and the only energy source for the nervous system. Carbohydrates consumed in the diet are broken down in the body to their simplest form- glucose, which is absorbed by the intestines and transported by the blood to various organs. Glucose is subsequently utilized by cells of these organs to produce energy wherever necessary, and the excess is stored either as glycogen in the liver for short-term storage or in fat tissues as triglycerides for long-term storage. The uptake, utilization, and storage of glucose after it is absorbed in the intestines are facilitated by the hormone- insulin secreted by the pancreas. Insulin influences the transport of glucose to the organs requiring it, like the heart, brain, working muscles, etc. It also directs storage of excess glucose. The action of insulin reduces sugar levels in the blood.

After a meal, sugar levels increase in blood and insulin is secreted in response to reduce sugar levels until it becomes normal. If glucose levels fall too low in blood, another pancreatic hormone called glucagon is released, which directs the liver to convert stored glycogen into glucose and release it into the blood. The insulin and glucagon hormones create a feedback mechanism to keep blood glucose levels within the normal range. Imbalance in their activity causes an excess or shortage of blood sugar.

The fasting glucose test checks the level of blood sugar levels during a period of fasting. This helps to determine if the body is able to utilize or store glucose efficiently. Excess sugar in blood indicates it is not being utilized or stored. This is principally caused due to Diabetes. Type 1 Diabetes is caused when insulin is not produced or produced in very little quantity. Type 2 Diabetes is caused when insulin produced is not utilized effectively by the body. In both these cases, blood sugar level rises, while cells are deprived of nutrition.

This test is performed on a blood sample. A syringe with a fine needle attached is used to withdraw blood sample from a blood vessel in your arm generally from the inner side of the elbow area. The doctor, nurse or the phlebotomist will tie an elastic band around your arm which will help the blood vessels to swell with blood and hence makes it easier to withdraw blood. You may be asked to tightly clench your fist. Once the veins are clearly visible, the area is cleaned with an antiseptic solution and then the needle is inserted into the blood vessel to collect the sample. You may feel a tiny pinprick during the procedure. Blood sample once collected is then sent to the laboratory.

There is no risk associated with the test. However, as this test involves a needle prick to withdraw the blood sample, rarely, a patient may experience increased bleeding, hematoma (blood collection under the skin) formation, bruising or infection at the site of needle prick.

Hyperglycemia refers to a condition where the blood glucose level is above the normal range. This condition may indicate prediabetes or diabetes and may cause significant health problems.

Symptoms of Hyperglycemia include: Increased thirst, frequent urge to urinate, weakness, tiredness (fatigue), blurring of vision and slow wound healing.

Hypoglycemia is the condition where the blood sugar levels fall below normal. This is commonly found in case of nutritional deficiency.

Symptoms of Hypoglycemia include: Excessive sweating, frequent hunger, shivering or trembling, confusion and blurring of vision

The risk factors for diabetes are:nBeing Obese or overweight with low physical inactivity, having a blood relative diagnosed with Diabetes, having been diagnosed with hypertension, having low High Density Lipoproteins or high triglyceride levels, being diagnosed with Polycystic Ovarian Syndrome, having been diagnosed with gestational diabetes and cardiovascular diseases.

Inform the doctor about any medications you may be taking. No other specific preparations are usually required before this test.

Yes, blood sugar levels can be increased by certain medications, during pregnancy, and even temporarily due to stress.

Diabetes causes an increase in blood sugar levels. Increased sugar levels, if not controlled, can cause severe damage to the muscles and nerves. This may give rise to a number of complications over a period of time. Some common complications of uncontrolled diabetes include: Heart diseases like coronary artery disease, heart attack ; Diabetic Retinopathy (damage to the retina) which may cause blindness; Diabetic Neuropathy (damage to the nerves) at various parts of the body; Diabetic Nephropathy (damage to the kidneys) resulting in chronic loss of kidney function; Diabetic foot which causes development of ulcers on the foot which may easily become gangrenous. Apart from these, uncontrolled diabetes may also lead to other severe conditions like hearing impairment, a number of skin conditions, and may even lead to death.

Additional tests that may be prescribed to diagnose diabetes in case of abnormal fasting blood glucose test result are: Urine Glucose Test, Blood Glucose - Post prandial (PP), Random Blood Glucose Test, Glycosylated Hemoglobin Test or HbA1c Test and Oral Glucose Tolerance Test.