Understanding Blood Sugar: What It Is and Why It Matters

Blood sugar, also known as blood glucose, is one of the most important elements of human health. It refers to the amount of glucose present in the bloodstream. Glucose is a type of sugar that serves as the body’s main source of energy. It comes from the food we eat—particularly carbohydrates—and is essential for fueling the brain, muscles, and other vital organs.

How Blood Sugar Works

When we eat food containing carbohydrates, such as bread, rice, fruit, or sweets, our digestive system breaks it down into glucose. This glucose is then absorbed into the bloodstream, where it can be transported to cells throughout the body. However, for glucose to enter cells and be used as energy, the body needs a hormone called insulin, which is produced by the pancreas.

Insulin acts like a key that "unlocks" cells so that glucose can enter. After a meal, blood sugar levels rise, signaling the pancreas to release insulin. Once glucose enters the cells and is either used for energy or stored for later use, blood sugar levels gradually decrease to a normal range.

Normal Blood Sugar Levels

Blood sugar levels fluctuate throughout the day depending on what and when you eat, how much you exercise, and even how much stress you're under. However, there are standard measurements for what is considered a normal blood sugar range:

Fasting blood sugar (before eating): 70 to 99 mg/dL

After eating (postprandial): Less than 140 mg/dL (1–2 hours after meals)

Hemoglobin A1c (average over 3 months): Below 5.7%

When blood sugar levels fall outside of these ranges—either too high or too low—it can lead to health issues.

High Blood Sugar: Hyperglycemia

High blood sugar, or hyperglycemia, occurs when there is too much glucose in the blood. This can happen if the body doesn’t produce enough insulin (as in type 1 diabetes) or if the body becomes resistant to insulin (as in type 2 diabetes). Other causes can include stress, illness, medications, or poor dietary choices.

Common symptoms of high blood sugar include:

Frequent urination

Increased thirst

Fatigue

Blurred vision

Headaches

If high blood sugar persists for a long time, it can damage organs and lead to complications such as heart disease, nerve damage, kidney failure, and vision loss.

Low Blood Sugar: Hypoglycemia

Low blood sugar, or hypoglycemia, happens when glucose levels drop too low—generally below 70 mg/dL. This can be dangerous, especially for people with diabetes who are taking insulin or certain medications.

Symptoms of low blood sugar include:

Shakiness

Sweating

Rapid heartbeat

Dizziness

Irritability

Confusion

Fainting in severe cases

To quickly raise blood sugar, a person can consume fast-acting carbohydrates like juice, glucose tablets, or candy.

Managing Blood Sugar

Maintaining stable blood sugar levels is important for everyone, not just people with diabetes. Stable levels support sustained energy, mood stability, and long-term health. Here are some key strategies for managing blood sugar:

1. Healthy Eating

Choosing foods with a low glycemic index (GI) can help prevent spikes in blood sugar. These include whole grains, legumes, leafy vegetables, and most fruits. Avoiding sugary drinks, processed foods, and refined carbs is also important.

2. Regular Exercise

Physical activity helps the body use glucose more effectively. It improves insulin sensitivity and helps lower blood sugar levels naturally. Even a 30-minute walk can make a difference.

3. Monitoring Blood Sugar

People with diabetes often use a glucometer or continuous glucose monitor (CGM) to track their levels throughout the day. Even those without diabetes may benefit from understanding how their body responds to different foods and activities.

4. Medication and Insulin

For those with diabetes, medications or insulin therapy may be necessary to manage blood sugar. These should be taken exactly as prescribed by a healthcare provider.

5. Stress Management

Chronic stress can raise blood sugar levels due to the release of stress hormones like cortisol. Techniques like meditation, deep breathing, and regular sleep can help maintain hormonal balance.

The Bottom Line

Blood sugar plays a central role in health and energy production. While our bodies are designed to regulate it automatically, lifestyle factors can have a significant impact. Understanding how blood sugar works and taking steps to manage it—through diet, exercise, and healthy habits—can prevent serious health problems and promote long-term well-being.

If you have concerns about your blood sugar or symptoms of diabetes, it's important to consult with a healthcare professional for proper testing and guidance.