Low Blood Sugar: Symptoms, Causes, and What You Need to Know
Low blood sugar, medically known as hypoglycemia, occurs when blood glucose levels drop below 2.8 mmol/L. For reference, normal fasting blood glucose levels in healthy individuals typically range between 3.9 and 6.0 mmol/L. When blood sugar falls too low, the body struggles to function properly, leading to a range of physical and neurological symptoms that can quickly escalate if not addressed.
Common Symptoms of Hypoglycemia
Hypoglycemia manifests in two primary ways, depending on how the body responds to low glucose levels:
1. Sympathetic Nervous System Activation
When blood sugar drops suddenly, the sympathetic nervous system kicks in as a defense mechanism. This often results in noticeable symptoms such as rapid heartbeat (palpitations), excessive sweating—even without physical exertion—and feelings of intense hunger. Many individuals also report sudden weakness, trembling, or a sensation of "shakiness." In some cases, patients may experience cold sweats and difficulty concentrating, which are early warning signs that the body needs glucose urgently.
2. Central Nervous System Impairment
If hypoglycemia is not corrected promptly, it can progress to affect the brain. Since the brain relies heavily on glucose for energy, insufficient levels can lead to confusion, dizziness, blurred vision, and even seizures. In severe cases, untreated low blood sugar may result in hypoglycemic coma, a life-threatening condition requiring immediate medical intervention.
Some people may also display behavioral changes, such as irritability, anxiety, or delirium—especially in elderly patients. These neuropsychiatric symptoms can sometimes be mistaken for other conditions like stroke or dementia, making accurate diagnosis essential.
Primary Causes of Low Blood Sugar
The most common cause of hypoglycemia is related to diabetes management. Individuals with diabetes who use insulin or take oral glucose-lowering medications—such as sulfonylureas—are at higher risk, especially if they:
- Skip or delay meals after taking medication
- Consume smaller portions than usual
- Engage in unexpected physical activity without adjusting food intake or dosage
In these situations, the medication continues to lower blood sugar, but without sufficient carbohydrate intake, levels can plummet dangerously low.
Medication-Related Factors
Even when patients follow their prescribed regimens, hypoglycemia can still occur due to incorrect dosing or improper timing of medications. Overuse of insulin or certain diabetes drugs can overwhelm the body's ability to maintain balance. If recurrent episodes happen despite proper eating habits, it's crucial to consult a healthcare provider for a thorough review and possible adjustment of treatment plans.
Less Common but Serious Causes
While rare, one underlying medical condition that can trigger persistent hypoglycemia is an insulinoma—a tumor of the pancreatic beta cells that produces excess insulin autonomously. These tumors are usually benign but require surgical removal. People with insulinomas often experience fasting hypoglycemia, particularly overnight or in the early morning, and may need specialized testing like a supervised 72-hour fast to confirm the diagnosis.
Other non-diabetes-related causes include liver disease, hormone deficiencies (like adrenal insufficiency), prolonged starvation, or certain medications unrelated to diabetes.
Prevention and Management Tips
Staying ahead of low blood sugar involves awareness and proactive habits. Diabetic patients should monitor their glucose regularly, especially before driving or operating machinery. Carrying fast-acting carbohydrates—such as glucose tablets, fruit juice, or hard candies—can provide quick relief during an episode.
For long-term safety, work closely with your doctor to fine-tune medication schedules, adjust doses based on lifestyle, and educate family members or coworkers about recognizing symptoms and administering emergency glucagon if needed.
Understanding the triggers and responses to hypoglycemia empowers individuals to manage their health more effectively and avoid potentially dangerous complications.