Convert between mg/dL and mmol/L, understand glucose levels and diabetes management
This tool is for educational purposes only and should not replace professional medical advice. Always consult your healthcare provider for diabetes management, medication adjustments, or concerns about blood sugar levels. In case of emergency symptoms, seek immediate medical attention.
HbA1c measures your average blood sugar over the past 2-3 months. It's expressed as a percentage and is the gold standard for diabetes management.
Below 5.7%
Average glucose: 77-117 mg/dL
Low diabetes risk
5.7% - 6.4%
Average glucose: 117-154 mg/dL
Increased risk
6.5% or higher
Average glucose: 154+ mg/dL
Diagnosis threshold
Below 7.0%
Average glucose: <154 mg/dL
ADA recommendation
Blood glucose is measured using two primary units worldwide. The United States primarily uses mg/dL (milligrams per deciliter), while most other countries use mmol/L (millimoles per liter). Understanding both units is essential when traveling or reading international medical literature.
Blood sugar levels vary throughout the day and are influenced by food, exercise, stress, medications, and other factors. Here are the standard reference ranges:
| Test Type | Normal | Pre-diabetes | Diabetes |
|---|---|---|---|
| Fasting (8+ hours) | 70-99 mg/dL (3.9-5.5 mmol/L) |
100-125 mg/dL (5.6-6.9 mmol/L) |
126+ mg/dL (7.0+ mmol/L) |
| 2-hour Post-meal | Less than 140 mg/dL (Less than 7.8 mmol/L) |
140-199 mg/dL (7.8-11.0 mmol/L) |
200+ mg/dL (11.1+ mmol/L) |
| Random (any time) | 80-140 mg/dL (4.4-7.8 mmol/L) |
140-199 mg/dL (7.8-11.0 mmol/L) |
200+ mg/dL (11.1+ mmol/L) |
| HbA1c | Less than 5.7% | 5.7% - 6.4% | 6.5% or higher |
Fasting Blood Sugar: Measured after not eating for at least 8 hours. This test shows how well your body manages blood sugar without food influence. It's the most reliable baseline measurement.
Postprandial (Post-meal): Measured 2 hours after eating. This shows how efficiently your body processes glucose from food. Normal metabolism should return blood sugar to near-normal levels within 2 hours.
Random Blood Sugar: Measured at any time regardless of when you last ate. Useful for monitoring throughout the day but less standardized than fasting tests.
HbA1c (Glycated Hemoglobin): Shows average blood sugar over 2-3 months. Glucose attaches to hemoglobin in red blood cells, providing a long-term picture of blood sugar control.
Food and Carbohydrates: All carbohydrates break down into glucose, raising blood sugar. Simple carbs (sugars) cause rapid spikes, while complex carbs provide gradual increases.
Physical Activity: Exercise typically lowers blood sugar by increasing glucose uptake by muscles. However, intense exercise can temporarily raise blood sugar due to stress hormones.
Stress and Illness: Physical and emotional stress release hormones (cortisol, adrenaline) that can significantly raise blood sugar levels.
Medications: Many medications affect blood sugar, including steroids, some blood pressure medications, and certain antidepressants.
Sleep and Hydration: Poor sleep and dehydration can both contribute to higher blood sugar levels and reduced insulin sensitivity.
Blood sugar below 70 mg/dL (3.9 mmol/L) is considered hypoglycemic. Symptoms include:
Treatment: Follow the "15-15 rule" - consume 15g of fast-acting carbs, wait 15 minutes, and retest. Repeat if still low.
Persistently elevated blood sugar can lead to serious complications. Acute symptoms include:
Chronic high blood sugar can damage blood vessels and organs over time:
Dietary Approaches: Focus on balanced meals with controlled carbohydrate portions. Consider the glycemic index of foods and practice portion control. Regular meal timing helps maintain stable levels.
Exercise Benefits: Both aerobic exercise and resistance training improve insulin sensitivity. Even short walks after meals can significantly reduce post-meal blood sugar spikes.
Monitoring Frequency: Type 1 diabetics may need to test 4-6 times daily, while Type 2 diabetics might test 1-2 times daily or as recommended by their healthcare provider.
Technology: Continuous Glucose Monitors (CGMs) provide real-time readings and trends, helping identify patterns and prevent dangerous highs or lows.
Low: <70 mg/dL (<3.9 mmol/L)
High: >250 mg/dL (>13.9 mmol/L)
Seek medical help immediately
Fasting: 80-130 mg/dL
Post-meal: <180 mg/dL
HbA1c: <7.0% (ADA goal)
100 mg/dL ≈ 5.6 mmol/L
180 mg/dL ≈ 10.0 mmol/L
Divide mg/dL by 18 for mmol/L
Annual screening: Age 35+
Every 3 years if normal
More frequent if risk factors
Immediate Emergency: Blood sugar below 50 mg/dL (2.8 mmol/L) or above 400 mg/dL (22.2 mmol/L), especially with symptoms of ketoacidosis.
Schedule Appointment: Consistently elevated readings, new symptoms, or questions about diabetes management. Regular check-ups are essential for optimal diabetes care.
Diabetes Prevention: If you have pre-diabetes, lifestyle changes including diet modification, regular exercise, and weight management can often prevent or delay Type 2 diabetes onset.