Glucose and Diabetes: All You Need to Know

The Biomarker Handbook is a curated series that seeks to provide readers with insights on each biomarker we cover in our blood test packages and its relation to our body.

Glucose is considered as the primary source of energy, which is required for the normal functioning of the organs in the body.

The blood glucose level is the amount of glucose circulating in the blood, which is tightly regulated by a number of hormones and pathways. The human body stores excess glucose in the liver in the form of glycogen, with the help of insulin hormone which is released from the pancreas. When fasting, blood glucose is kept at normal levels by conversion of stored glycogen into glucose.

What Is Diabetes and How Is It Diagnosed?

American Diabetes Association (ADA) defines diabetes as a group of metabolic diseases characterised by hyperglycaemia (high blood sugar) resulting from defects in insulin secretion, insulin action, or both. Did you know that the number of people with diabetes has increased from 108 million in 1980 to 422 million in 2014? Globally, there are nearly 1.6 million deaths caused by diabetes in 2015.

There are three main tests to diagnose diabetes. These tests should be repeated to confirm the diagnosis of diabetes (unless symptoms of diabetes are already present - in which case only one test result is sufficient for diagnosis).

  1. Fasting blood sugar test

In this test, patients should not eat or drink anything with the exception of water for at least 8 hours.

Diabetes is diagnosed if fasting blood sugar is greater than or equal to 7.0 mmol/L. Normal blood glucose fasting level should be between 3.5 to 5.5 mmol/L. If your blood glucose fasting level is between 5.6 – 6.9 mmol/L, you are considered to be prediabetic - intolerant to glucose and have a higher risk of developing diabetes and it is important that you take care of your glucose levels.

  1. Oral glucose tolerance test (OGTT)

This test measures how well you are able to restore glucose to normal levels after ingestion of a specific amount of glucose (75 gms). OGTT begins with measuring fasting blood sugar.

Diabetes is diagnosed if the blood level, after two hours of ingestion of this glucose solution, is 11.1 mmol/L or more. Normal postprandial glucose level should be below 7.8  mmol/L. If postprandial glucose level is between 7.8 – 11.0 mmol/L, you will be diagnosed with prediabetes. There is a strong association between prediabetes (especially impaired postprandial glucose tolerance) and risk of coronary heart disease and stroke.

  1. Glycated haemoglobin (A1C)

This test measures the average blood glucose for the past 2 to 3 months. Diabetes is diagnosed if HbA1c is 6.5% or higher. Normal individuals have HbA1c levels of less than 5.7%. Prediabetes is diagnosed if HbA1c is 5.7% to 6.4%.

What Are the Types of Diabetes?

  1. Type 1 diabetes is also known as juvenile diabetes and occurs when the pancreas stops producing insulin, leading to high glucose levels. It usually occurs during childhood or adolescence and requires insulin injections.
  2. Type 2 diabetes is the most common type of diabetes, where your body does not utilise insulin properly. Up to 18% of Malaysian adults suffer from this condition. Type 2 diabetes is generally feared for its many complications including kidney failure and heart disease.
  3. Gestational diabetes is a type of diabetes which develops only during pregnancy. The high blood sugar can seriously affect your pregnancy and your baby’s health, so it is very important for gestational diabetic patients to control their blood sugar level within the normal range. Most doctors prescribe insulin to gestational diabetic patients.

Signs and Symptoms of Diabetes

  • Frequent urination
  • Hunger and fatigue
  • Dry mouth
  • Itchy skin
  • Blurred vision
  • Feeling thirsty often
  • Weight loss
  • Numbness in the hands or feet
  • Slow healing bruises

Treatment of Diabetes

The primary goal of the management of diabetes is to keep blood glucose at a normal tight range, in order to avoid or reduce the rate of complications associated with diabetes as seen below. Treatment always involves lifestyle and dietary actions, and in some cases daily medication for the rest of your life. The ADA recommends that diabetics maintain an optimal fasting glucose between 4.4 – 7.2 mmol/L.

Engaging in physical exercise, eating healthy food, minimizing the amount of carbohydrates and saturated fats are very important steps for the management of diabetes.

Metformin is the first-choice medication prescribed for type 2 diabetic patients who are overweight. It improves the sensitivity of body cells to insulin so that insulin can function more effectively. Other oral anti-diabetic drugs such as sulfonylureas, meglitinides, and thiazolidinediones may also be used.

If oral anti-diabetic drugs fail to lower blood glucose level to the normal range, insulin therapy may be the best choice. In fact, insulin therapy is the first choice in gestational diabetes, type 1 diabetes, and some people who have type 2 diabetes.

Hypoglycaemia and Diabetes

Hypoglycaemia, or low blood sugar, occurs when blood sugar level falls too low to meet the body demands.

It is the most common complication of diabetes treatment. If diabetic patients take an overdose of insulin or other diabetes medications, hypoglycaemia will occur. When your blood sugar is below 4 mmol/L or you have symptoms of hypoglycaemia (palpitations, anxiety, sweating, shakiness, irritability, and fatigue), you must follow a protocol of hypoglycaemia including drinking 15g of glucose immediately (1/2 cup of normal fruit juice or normal soda), wait for 15 minutes and remeasure the blood glucose level. If it is still below 4 mmol/L, drink another 15g of glucose and call your doctor immediately. If you are unable to drink the 15g of glucose, inject glucagon if available and call the ambulance.

Diabetes Complications

Diabetes is often referred to as a “silent killer” since many people with diabetes do not notice any major problems until later stages of the disease. Diabetes continues to damage organs because it can go unnoticed for several years. One of the most common diabetes complications is heart disease.

Hyperglycaemia may damage arteries and make them more likely to develop atheroma (fatty deposits). The real problem happens if atheroma occurs inside the coronary arteries which supply oxygen-rich blood and nutrients to the heart. This can cause angina pectoris (chest pain or discomfort due to coronary heart disease) and heart attack.

Another common diabetes complication is stroke, which occurs when blood supply to brain cells is interrupted or reduced. Without immediate medical treatment, brain cells begin to die. Symptoms of stroke include paralysis or numbness in the face, arm or leg, trouble with speaking and understanding, trouble seeing, and dizziness.

Hyperglycaemia destroys tiny blood vessels in the kidney. Over time, the kidney will not effectively filter the blood and kidney damage or diabetic nephropathy is likely to occur. Diabetic patients should check their kidney health regularly with urine analysis, urine protein, eGFR and creatinine clearance. Hyperglycaemia can also harm human nerves, a medical condition known as diabetic neuropathy. If you feel pain, numbness, or burning sensation in your hands or feet, tell your doctor as soon as possible.

Screening for Diabetes

Everyone should be screened for type 2 diabetes, particularly if they are overweight (BMI ≥ 25 kg/m2) and if they have one or more of the following risk factors: first-degree relative with diabetes, women who delivered a baby weighing > 4 kg, diagnosis of hypertension > 140/90 mmHg, diagnosis of polycystic ovarian syndrome, or history of gestational diabetes mellitus (GDM).


Though diabetes is a chronic disease and often leads to serious medical problems, diabetic patients with controlled blood glucose levels with the right diet and lifestyle can enjoy a healthy life and prevent or delay complications. The paramount importance of diabetes management: keep your sugars at normal levels to stay healthy.

If you want to find out more about how you can manage or prevent diabetes, take a look at our lifestyle article here!

Interested in other biomarkers? Check out the rest of The Biomarker Handbook.

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