Fasting Blood Glucose 318 mg/dL: Is That High?

Is Fasting Blood Glucose 318 mg/dL Low, Normal, or High?

Fasting glucose 318 mg/dL is considered high and falls well into the diabetes range. The American Diabetes Association defines diabetes as fasting glucose of 126 mg/dL or above, and at 318 mg/dL your blood sugar is significantly elevated after an overnight fast. This result needs medical attention. The important thing to understand is that diabetes is manageable, and taking action now can make a meaningful difference in your health outcomes.

A fasting blood glucose reading of 318 mg/dL signals severe hyperglycemia, unequivocally placing you in the diagnostic range for diabetes, whether type 1 if previously unmanaged, or new onset type 2. This level is significantly above the normal 70-99 mg/dL range and demands prompt medical attention. Such a high value often stems from pronounced insulin resistance, where cells fail to utilize insulin effectively, or from inadequate insulin production by the pancreas. It can also be exacerbated by recent illness, stress, or a prolonged period of unmanaged elevated blood sugar. To confirm this diagnosis and understand its impact, your provider will typically order an HbA1c test, which reflects your average blood sugar over the past 2-3 months, alongside a repeat fasting glucose. Further evaluations might include tests for kidney function and, if type 1 diabetes is suspected, specific autoantibody screenings. While this number is alarming, understand that effective management, often involving lifestyle modifications and medication, can typically lower blood glucose significantly. The crucial immediate step is to safely reduce your blood sugar to mitigate the risk of acute, life-threatening complications like diabetic ketoacidosis, which requires urgent care. Your proactive engagement with your healthcare team is paramount.

Hidden Risk of Fasting Blood Glucose 318 mg/dL

A fasting glucose of 318 mg/dL can feel abstract because high blood sugar often does not cause pain or obvious discomfort in the short term. That is part of what makes it dangerous. Elevated glucose works quietly in the background, and the damage it causes accumulates over months and years before symptoms appear. The American Diabetes Association emphasizes that early management is critical because complications are much harder to reverse than to prevent.

A fasting blood glucose level of 318 mg/dL significantly elevates the risk of acute hyperglycemic crises such as hyperosmolar hyperglycemic state (HHS), a life-threatening condition characterized by extreme dehydration and neurological impairment. Prolonged hyperglycemia at this magnitude also accelerates microvascular damage, leading to a higher likelihood of developing retinopathy, nephropathy, and neuropathy over a shorter timeframe. The osmotic diuresis caused by such high glucose levels can lead to electrolyte imbalances and kidney strain, further exacerbating potential long-term organ damage. Arterial wall inflammation is also heightened, increasing the risk of macrovascular complications like heart attack and stroke even in the absence of overt pre-existing cardiovascular disease.

• Persistently high blood sugar damages the small blood vessels in your eyes, a condition called diabetic retinopathy, which is the leading cause of blindness in working-age adults
• Elevated glucose causes nerve damage (neuropathy) that often starts as tingling or numbness in the feet and hands and can progress to chronic pain or loss of sensation
• The kidneys filter excess glucose from the blood, and over time this overwork can lead to diabetic kidney disease, which the National Kidney Foundation reports affects about 1 in 3 people with diabetes
• Heart disease risk is two to four times higher in people with diabetes compared to those without, according to the American Heart Association
• High blood sugar impairs wound healing and weakens the immune system, making infections more common and harder to clear

What Does a Fasting Blood Glucose Level of 318 mg/dL Mean?

Glucose is the sugar your cells use for energy. When you eat, carbohydrates break down into glucose and enter the bloodstream. Normally, the pancreas releases insulin to move glucose from the blood into cells. Fasting glucose measures your blood sugar after at least 8 hours without food, showing how well your body manages glucose on its own.

A fasting blood glucose reading in the range of 318 mg/dL most commonly points to poorly controlled type 2 diabetes, potentially exacerbated by a recent high carbohydrate meal or a period of reduced physical activity. Another significant possibility is undiagnosed type 1 diabetes, where the body is producing little to no insulin, leading to rapid glucose accumulation. Medication non-adherence or an insufficient dosage of insulin or oral hypoglycemic agents in a known diabetic patient is also a strong contender. Less frequently, but still plausible, are conditions like Cushing's syndrome or pancreatitis which can impair glucose regulation.

At 318 mg/dL, your fasting glucose is roughly 80 points above the normal ceiling of 99 mg/dL. This tells you that your body's glucose regulation system is significantly impaired. Either your pancreas is not producing enough insulin, your cells are highly resistant to the insulin being produced, or both.

In type 2 diabetes, which accounts for about 90 to 95 percent of all diabetes cases, the primary issue is insulin resistance. Your cells stop responding efficiently to insulin, so glucose accumulates in the blood. The pancreas tries to compensate by producing more insulin, but eventually cannot keep up. By the time fasting glucose reaches 318 mg/dL, this process has usually been underway for some time.

In type 1 diabetes, the immune system destroys the insulin-producing cells in the pancreas, leading to little or no insulin production. This can cause blood sugar to rise quickly and often requires insulin therapy from the start. Your doctor can determine which type applies to you based on additional tests.

Lifestyle Changes for Fasting Blood Glucose 318 mg/dL

Lifestyle changes are a fundamental part of managing fasting glucose at 318 mg/dL, and they work alongside whatever medical treatment your doctor prescribes. Exercise is especially powerful for people with high blood sugar because physical activity directly lowers glucose by moving it from the blood into working muscles, even without insulin.

Immediately schedule an urgent appointment with your primary care physician or an endocrinologist; do not wait for your next scheduled visit. Your physician will likely order a hemoglobin A1c test to assess long-term glucose control and a urinalysis for ketones and protein. Until your appointment, strictly limit intake of all sugars and refined carbohydrates and increase fluid intake with water. If you are prescribed diabetes medication, do not adjust the dosage yourself but be prepared to discuss adherence and effectiveness with your doctor. Begin tracking your blood glucose levels multiple times daily to provide a clearer picture of your glycemic fluctuations.

The American Diabetes Association recommends at least 150 minutes of moderate aerobic exercise per week. Walking, cycling, swimming, or dancing all count. Start where you are. If 30 minutes feels like too much, start with 10-minute walks after meals and build from there. Post-meal walking is particularly effective because it blunts the blood sugar spike that follows eating.

Weight management plays a major role. Losing 5 to 10 percent of your body weight can dramatically improve insulin sensitivity and lower fasting glucose. For a 200-pound person, that is 10 to 20 pounds. You do not need to reach a target weight. Every pound lost in the right direction helps your body manage glucose better.

Smoking and diabetes are a particularly harmful combination. Smoking increases insulin resistance, raises blood sugar, and accelerates all of the vascular complications that diabetes can cause. If you smoke, quitting is one of the highest-impact changes you can make for your diabetic health.

Stress management is not optional when blood sugar is this elevated. Cortisol, the stress hormone, tells your liver to release more glucose into the bloodstream. Chronic stress keeps cortisol elevated, which keeps blood sugar elevated. Find a stress reduction practice that works for you and use it regularly.

Written by

Ernestas K.

Clinical research writer specializing in human health, biology, and preventive medicine.

Reviewed against ADA, CDC, NIH, WHO, Mayo Clinic guidelines · Last reviewed March 20, 2026