Monitoring blood glucose levels is fundamental for managing diabetes and understanding metabolic health. Since glucose is the body’s primary energy source, maintaining it within a healthy range is necessary for the proper functioning of organs, especially the brain. While a blood glucose meter or a continuous glucose monitor (CGM) provides an accurate, quantitative number, sometimes a person needs to assess their sugar status without a device. In these situations, the body’s physical and neurological responses become the only available indicators, signaling when a level is dangerously out of range.
Assessing Symptoms of Low Blood Sugar (Hypoglycemia)
Recognizing the signs of low blood sugar, typically defined as a blood glucose level falling below 70 milligrams per deciliter (mg/dL), is an immediate safety measure. The body initially reacts to falling glucose by releasing hormones like epinephrine, which trigger noticeable physical responses. These adrenergic symptoms serve as the body’s alarm, attempting to raise glucose levels by stimulating the liver to release stored sugar.
The physical manifestations often include shakiness or tremors, excessive sweating, and a rapid or irregular heartbeat. These symptoms occur because the body perceives the glucose deficit as a fight-or-flight emergency, activating the sympathetic nervous system. Individuals may also feel intense, sudden hunger, anxiety, or irritability.
As blood glucose continues to drop, the brain, which relies almost exclusively on glucose for fuel, begins to suffer from a lack of energy, leading to neuroglycopenic symptoms. This stage manifests as difficulty concentrating, confusion, dizziness, and slurred speech. If not corrected, these symptoms can progress to severe disorientation, loss of coordination, seizures, and eventually unconsciousness.
Assessing Symptoms of High Blood Sugar (Hyperglycemia)
The symptoms of high blood sugar, or hyperglycemia, usually develop more slowly than those of hypoglycemia, often appearing when levels exceed 180 to 200 mg/dL. The primary signs stem from the kidneys attempting to excrete the excess glucose through urine. This process requires water, leading to the classic symptoms of excessive thirst (polydipsia) and frequent urination (polyuria).
This loss of fluid can cause dehydration, which contributes to overall fatigue and weakness. High sugar levels also affect the lens of the eye, causing temporary blurred vision as fluid shifts. Over time, chronic hyperglycemia can impair circulation and nerve function, leading to slow-healing cuts or recurrent infections.
When hyperglycemia is severe and prolonged, especially in people with Type 1 diabetes, the body may break down fat for energy, producing acidic byproducts called ketones. This state, known as diabetic ketoacidosis (DKA), represents a medical emergency. DKA symptoms include a characteristic fruity odor on the breath, nausea, vomiting, and abdominal pain, signaling a life-threatening buildup of acidity.
Current Status of Non-Invasive Testing Technologies
The search for a truly non-invasive blood glucose monitor that provides quantitative, meter-accurate results has been ongoing for decades. Currently, no widely available consumer-grade device, such as a smartwatch or a ring, can reliably and accurately quantify blood glucose using light or other non-puncture methods. The challenge lies in isolating the glucose signal from the noise created by other components in the skin, sweat, or interstitial fluid, which are easily affected by temperature and movement.
Many commercially available devices, sometimes mistakenly called non-invasive, are actually minimally invasive Continuous Glucose Monitors (CGMs). These systems use a tiny sensor filament inserted just under the skin to measure glucose in the interstitial fluid. Recent advancements have led to the FDA clearance of over-the-counter CGMs for individuals who do not use insulin, expanding access to quantitative tracking without a prescription.
Future technologies in development are exploring methods like Raman spectroscopy, which uses light to analyze the chemical composition of tissue, and breath analysis, to measure glucose levels. While these technologies show promise in clinical trials, they are not yet ready for widespread consumer use as accurate, standalone measurement tools. Symptom recognition remains the primary non-meter method for assessing blood sugar status until these non-puncture methods demonstrate medical-grade accuracy and receive full regulatory approval.
Immediate Steps When Symptoms Are Severe
Symptom recognition functions as a warning system, not a measurement tool, and severe symptoms necessitate immediate action. If symptoms point to severe hypoglycemia, the immediate step is to consume a fast-acting carbohydrate source containing 15 to 20 grams of sugar. Examples include four ounces of juice, regular soda, or glucose tablets, which are quickly absorbed into the bloodstream.
If the person is confused or unable to swallow safely, do not attempt to give them food or drink due to the choking hazard. In this severe state, a glucagon injection or nasal spray must be administered immediately if available, as this hormone signals the liver to release stored glucose.
For suspected severe hyperglycemia, particularly if nausea or vomiting is present, the immediate priority is hydration and seeking medical attention. Severe symptoms of either hypo- or hyperglycemia are medical emergencies that require professional intervention to prevent complications like coma.