Blood Sugar Checker & Converter

Blood Sugar Checker -- Is Your Blood Glucose Normal, High or Low?
Blood Sugar Checker -- Is Your Blood Glucose Normal, High or Low? | Daily Health Tools
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Diabetes and Metabolic Tool

Blood Sugar Checker
Is Your Glucose Normal, High or Low?

Enter your blood glucose reading to instantly check your category and diabetes risk. Converts between mmol/L and mg/dL automatically. Get personalised action plan, WhatsApp share card, and free PDF report. Based on ADA and WHO guidelines.

ADA and WHO Guidelines
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⚠ Medical Disclaimer: This tool is for informational purposes only. A single blood sugar reading does not diagnose diabetes or hypoglycaemia. Diabetes diagnosis requires two abnormal readings on separate occasions. Always consult your doctor for proper interpretation and treatment. If you have symptoms of severe high or low blood sugar, seek immediate medical attention.
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Converted value: - mg/dL (1 mmol/L = 18.0182 mg/dL)
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Content reviewed against American Diabetes Association (ADA) 2024 Standards of Care, WHO diabetes diagnosis guidelines, and peer-reviewed diabetes management research. Last updated: July 2026.
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What Are Normal Blood Sugar Levels?

Normal fasting blood sugar (8+ hours without food) is 3.9-5.6 mmol/L (70-100 mg/dL) per ADA guidelines. Post-meal blood sugar (2 hours after eating) should be under 7.8 mmol/L (under 140 mg/dL). Prediabetes is diagnosed at 5.6-6.9 mmol/L fasting or 7.8-11.0 mmol/L post-meal. Diabetes is diagnosed at 7.0+ mmol/L fasting (126+ mg/dL) on two separate tests.

Blood sugar levels naturally fluctuate throughout the day -- rising after meals and falling during fasting and exercise. The goal of diabetes management is not to eliminate these fluctuations but to keep glucose within a healthy range most of the time. Even in people without diabetes, blood sugar rises after every meal, then returns to the fasting range within 2 hours.

HbA1c (glycated haemoglobin) provides a 3-month average of blood sugar levels and is the gold standard for diabetes monitoring. An HbA1c under 5.7% is normal; 5.7-6.4% indicates prediabetes; 6.5%+ confirms diabetes. Unlike single blood sugar readings, HbA1c is not affected by recent meals, stress, or illness. Check your diabetes risk with our Diabetes Risk Score Calculator.

How to Convert Blood Sugar Units -- mmol/L and mg/dL

To convert blood sugar from mmol/L to mg/dL: multiply by 18.0182. To convert from mg/dL to mmol/L: divide by 18.0182. Example: 5.5 mmol/L x 18 = 99 mg/dL. Or 180 mg/dL divided by 18 = 10.0 mmol/L. The UK, Europe, Australia, Pakistan, and most of the world use mmol/L. The USA uses mg/dL.

Fasting vs Post-Meal Blood Sugar -- Key Differences

CategoryFasting (mmol/L)Fasting (mg/dL)2h Post-Meal (mmol/L)2h Post-Meal (mg/dL)
Normal3.9-5.670-100Under 7.8Under 140
Prediabetes5.6-6.9100-1257.8-11.0140-199
Diabetes7.0+126+11.1+200+
HypoglycaemiaBelow 3.9Below 70Below 3.9Below 70
Severe HypoglycaemiaBelow 3.0Below 54Below 3.0Below 54
Dangerous High16.7+300+16.7+300+

Fasting blood sugar and post-meal blood sugar give different information. Some people have normal fasting glucose but elevated post-meal spikes (postprandial hyperglycaemia) -- this still increases cardiovascular and diabetes risk. Post-meal testing 2 hours after the first bite of food is particularly useful for detecting early impaired glucose tolerance. Check your insulin resistance levels with our HOMA-IR Calculator.

What Is Prediabetes? Everything You Need to Know

Prediabetes is a metabolic state where blood glucose is higher than normal but not yet high enough for a diabetes diagnosis. It affects approximately 37% of US adults and similar proportions globally, with most people unaware they have it. Prediabetes is a critical warning stage -- most type 2 diabetes cases pass through prediabetes first, and up to 70% of people with prediabetes will develop type 2 diabetes without intervention.

The good news: prediabetes is highly reversible. Landmark research (Diabetes Prevention Program) showed that lifestyle intervention -- 7% weight loss and 150 minutes of moderate exercise per week -- reduced diabetes risk by 58% in people with prediabetes. This is more effective than the diabetes medication metformin (which reduced risk by 31%). Use our Weight Loss Calculator to plan your target weight loss alongside blood sugar management.

High Blood Sugar (Hyperglycaemia) -- Causes, Symptoms and Risks

Causes of High Blood Sugar

  • Large, high-carbohydrate meals: Especially refined carbs (white bread, rice, sweets) that are rapidly absorbed and spike blood glucose
  • Physical inactivity: Exercise increases insulin sensitivity and glucose uptake by muscles -- sedentary behaviour does the opposite
  • Stress: Cortisol and adrenaline raise blood glucose as part of the fight-or-flight response. Chronic stress contributes to insulin resistance
  • Poor sleep: Even one night of poor sleep significantly impairs insulin sensitivity
  • Dehydration: Concentrated blood with less fluid means higher glucose concentration
  • Illness and infection: The body releases stress hormones during illness that raise blood glucose

Long-Term Complications of High Blood Sugar

Chronically elevated blood sugar damages blood vessels and nerves throughout the body:

  • Cardiovascular disease: The leading cause of death in diabetics -- high blood sugar damages artery walls and accelerates atherosclerosis. Monitor your blood pressure and cholesterol alongside glucose
  • Diabetic nephropathy (kidney disease): Excess glucose damages the kidneys' filtration system over years
  • Diabetic neuropathy: Nerve damage causing pain, numbness, and tingling, particularly in the feet
  • Diabetic retinopathy: Damage to retinal blood vessels, leading to vision loss
  • Impaired wound healing: High glucose impairs immune function and blood vessel health

Low Blood Sugar (Hypoglycaemia) -- When and Why It Happens

Low blood sugar is defined as below 3.9 mmol/L (70 mg/dL). Severe hypoglycaemia is below 3.0 mmol/L (54 mg/dL). Symptoms of low blood sugar include shakiness, sweating, dizziness, confusion, rapid heartbeat, and hunger. Treatment: consume 15-20g of fast-acting carbohydrates (glucose tablets, fruit juice, regular (not diet) soft drink, or 4-5 glucose sweets). Check again after 15 minutes.

Hypoglycaemia is most common in people on insulin or certain diabetes medications. In people without diabetes, low blood sugar is rare but can occur with prolonged fasting, intense exercise, excessive alcohol consumption, or certain medical conditions. Staying adequately hydrated supports stable blood glucose -- use our Water Intake Calculator for your daily hydration target.

How to Lower Blood Sugar Naturally

  1. Regular physical activity: Exercise is the most powerful tool for improving insulin sensitivity. A 10-15 minute walk after each meal significantly reduces post-meal blood glucose spikes. Our Steps to Calories Calculator can help you track daily activity
  2. Low-glycaemic index diet: Choose foods that release glucose slowly -- oats, legumes (dal, rajma, chickpeas), vegetables, whole grains, and berries. Find low-GI South Asian recipes on Daily Health Kitchen
  3. Reduce sugar intake: Check your daily sugar consumption with our Sugar Intake Calculator. WHO recommends under 25g of free sugar per day
  4. Weight loss: Losing 5-10% of body weight significantly improves insulin sensitivity and lowers fasting glucose. Use our Calorie Calculator and BMI Calculator
  5. Fibre-rich diet: Soluble fibre slows glucose absorption from the gut. Vegetables, legumes, oats, and flaxseed are excellent sources
  6. Portion control: Smaller meals more frequently produce smaller glucose spikes than large infrequent meals
  7. Stress management: Chronic stress raises cortisol, which directly raises blood glucose. Sleep, meditation, and exercise all reduce cortisol
  8. Adequate sleep: Even partial sleep deprivation increases insulin resistance by 20-25%. Prioritise 7-9 hours of quality sleep nightly
The single most effective lifestyle change for blood sugar management is a post-meal walk. Research shows that walking for just 10-15 minutes after each meal reduces the 2-hour post-meal blood sugar spike by 20-30%. This is because muscle contractions during walking absorb glucose from the blood without requiring insulin. Three 10-minute post-meal walks per day can transform blood sugar control without any dietary changes.

Frequently Asked Questions

Normal fasting blood sugar is 3.9-5.6 mmol/L (70-100 mg/dL). Normal post-meal (2h) is under 7.8 mmol/L (under 140 mg/dL). Prediabetes: 5.6-6.9 fasting or 7.8-11.0 post-meal. Diabetes: 7.0+ fasting (126+ mg/dL) or 11.1+ post-meal on two separate tests.
To convert mmol/L to mg/dL: multiply by 18. To convert mg/dL to mmol/L: divide by 18. Examples: 5.5 mmol/L = 99 mg/dL. 180 mg/dL = 10.0 mmol/L. The UK and most countries use mmol/L; USA uses mg/dL. This calculator converts automatically between both units.
Dangerous low (severe hypoglycaemia): below 3.0 mmol/L (54 mg/dL) -- treat immediately with fast-acting sugar. Dangerous high: above 16.7 mmol/L (300 mg/dL) warrants urgent medical attention. Above 27.8 mmol/L (500 mg/dL) or with vomiting, confusion, or rapid breathing is a medical emergency.
Prediabetes is blood sugar higher than normal but below the diabetes threshold. Fasting: 5.6-6.9 mmol/L (100-125 mg/dL). Post-meal: 7.8-11.0 mmol/L. HbA1c: 5.7-6.4%. It affects approximately 37% of adults, most without symptoms. Lifestyle changes (7% weight loss, 150 min exercise/week) reduce diabetes risk by 58%.
No diabetes: once a year during routine physical (for adults 45+ or those with risk factors). Prediabetes: every 3-6 months. Type 2 diabetes: at minimum daily fasting readings, plus post-meal when adjusting diet or medications. Type 1 diabetes: multiple times daily as directed by doctor. CGM (continuous glucose monitor) provides the most complete picture.
Temporary causes: large high-carbohydrate meals, physical inactivity, stress, illness, dehydration, poor sleep, and some medications (steroids). Persistent high blood sugar is caused by insulin resistance or insufficient insulin production (type 2 diabetes). Main risk factors: obesity (especially abdominal fat), physical inactivity, age, and family history.
Hyperglycaemia symptoms include increased thirst, frequent urination, fatigue, blurred vision, headache, and slow wound healing. These often develop gradually. Severe hyperglycaemia (DKA): fruity breath, vomiting, abdominal pain, rapid breathing, confusion -- this is a medical emergency. Type 2 diabetes often has no symptoms in early stages, which is why regular testing is essential.
Fasting blood sugar is measured after at least 8 hours without food or caloric beverages. It reflects baseline blood glucose without recent meal influence. Normal fasting blood sugar is 3.9-5.6 mmol/L (70-100 mg/dL). Above 7.0 mmol/L (126 mg/dL) on two separate tests confirms a diabetes diagnosis.

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