A blood glucose reading of 210 milligrams per deciliter (mg/dL) signifies a state of hyperglycemia, meaning the level of sugar circulating in the bloodstream is higher than the recommended target range. This reading is significantly high and requires attention.
For most adults without diabetes, a normal fasting blood sugar reading should be below 100 mg/dL, and a reading two hours after eating should generally be less than 140 mg/dL. For individuals managing diabetes, the common target range before a meal is 80 to 130 mg/dL, and less than 180 mg/dL one to two hours after a meal. A reading of 210 mg/dL exceeds both the pre-meal and post-meal goals, indicating the body is not effectively processing glucose due to insufficient insulin or insulin resistance.
While a single reading of 210 mg/dL is not typically a life-threatening emergency, it is associated with acute symptoms like increased thirst and frequent urination. Sustained levels above 180 to 200 mg/dL cause long-term damage to nerves, eyes, kidneys, and blood vessels. Taking corrective action is necessary to bring the glucose concentration back toward the safer therapeutic zone.
Common Triggers for Hyperglycemia
A spike to 210 mg/dL is often caused by acute factors or chronic issues with diabetes management. Acute causes include dietary factors, such as consuming a meal with a higher-than-expected carbohydrate count, or a missed or insufficient dose of insulin or oral diabetes medication.
Physiological stress from an illness, such as a cold, flu, or infection, triggers the release of stress hormones like cortisol, which work against insulin and raise blood sugar levels. Emotional stress, like family conflict or workplace pressure, can have a similar effect due to the surge of counter-regulatory hormones. Reduced physical activity also means muscles are not utilizing glucose as efficiently, contributing to the high reading.
If high readings are frequent, a chronic issue may indicate a need to adjust the baseline medication regimen. This requires a re-evaluation of insulin-to-carbohydrate ratios or oral medication dosages. Certain medications, such as steroids or immunosuppressants, are also known to significantly impair insulin function and drive up blood glucose levels.
Immediate Steps to Lower Blood Sugar
When a blood sugar reading of 210 mg/dL appears, the immediate goal is to safely lower it back into the target range. The first step is to increase fluid intake by drinking water, which helps flush out excess glucose through the kidneys. Proper hydration also helps prevent dehydration, a common symptom of high blood sugar.
For individuals who use insulin, a correction dose of rapid-acting insulin is the quickest and most effective method to address the high reading. This dose should only be administered according to a pre-approved plan established with a healthcare provider. The blood sugar should be rechecked after 15 to 30 minutes to confirm it is dropping, and taking a second dose too soon should be avoided to prevent a dangerous drop later.
Light physical activity, such as a brisk walk for 15 to 20 minutes, can also help lower blood sugar by increasing insulin sensitivity and prompting muscles to use glucose for energy. However, if the blood sugar is 240 mg/dL or higher, or if the individual feels ill, they must first check for ketones in their urine or blood. If ketones are present, exercise must be avoided, as physical exertion can raise glucose levels further and accelerate the development of a medical emergency.
When to Seek Emergency Medical Attention
While a reading of 210 mg/dL can usually be managed at home, certain accompanying symptoms signal that the hyperglycemia is progressing toward a life-threatening emergency, such as Diabetic Ketoacidosis (DKA) or Hyperosmolar Hyperglycemic State (HHS). If a person experiences persistent vomiting or is unable to keep any fluids down, emergency medical services should be called immediately. These symptoms indicate severe dehydration and a potential inability to reverse the high blood sugar without intravenous treatment.
Signs of a medical emergency include confusion, unusual behavior, or any significant change in mental status. Other serious warning signs are shortness of breath or deep, labored breathing (Kussmaul breathing), which is a sign of metabolic acidosis. A sweet or fruity odor on the breath, caused by the body producing high levels of ketones, also warrants an urgent trip to the emergency room. If a blood sugar reading remains stubbornly high despite following the home correction plan, or if a ketone test result is high, consultation with a medical professional is required.