mg/dL (milligrams per deciliter)
mmol/L (millimoles per liter)
Fasting (before meals)
1 Hour After Meal
2 Hours After Meal
Bedtime
Anytime (for general context)
Your Result:
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Understanding Blood Sugar Levels
Blood sugar, or glucose, is the primary source of energy for your body's cells. It comes from the food you eat and is transported to cells by insulin, a hormone produced by the pancreas. Maintaining blood sugar levels within a specific range is crucial for overall health. Both consistently high (hyperglycemia) and consistently low (hypoglycemia) blood sugar levels can lead to serious health complications.
This Blood Sugar Level Calculator helps you input your glucose reading and the context (unit of measurement, time of day) to provide a general interpretation based on common guidelines. It's important to remember that this tool is for informational purposes only and should not replace professional medical advice from a doctor or healthcare provider.
How the Calculator Works (Behind the Math)
The calculator takes your raw blood sugar reading and considers the unit of measurement (mg/dL or mmol/L) and the time of day. The core interpretation relies on established target ranges for blood glucose, which can vary slightly depending on the source and individual health status.
Unit Conversion:
If your reading is in mg/dL, and you want to see it in mmol/L, the conversion formula is:
mmol/L = mg/dL / 18.018
Conversely, to convert from mmol/L to mg/dL:
mg/dL = mmol/L * 18.018
The calculator performs this conversion internally to compare your reading against standardized ranges, regardless of the input unit.
Interpretation Logic:
The calculator uses general target ranges for non-diabetic individuals and common targets for people with diabetes. These are simplified and should be discussed with a healthcare professional.
Fasting Blood Sugar: Typically targets are:
Non-diabetic: 70-99 mg/dL (3.9-5.5 mmol/L)
Diabetic (target): 80-130 mg/dL (4.4-7.2 mmol/L)
2 Hours After a Meal: Typically targets are:
Non-diabetic: Less than 140 mg/dL (7.8 mmol/L)
Diabetic (target): Less than 180 mg/dL (10.0 mmol/L)
Anytime/Other Readings: These are harder to categorize without more context but generally:
Below 70 mg/dL (3.9 mmol/L) is considered hypoglycemia (low blood sugar).
Above 180 mg/dL (10.0 mmol/L) two hours after a meal or consistently high readings may indicate hyperglycemia (high blood sugar).
The calculator categorizes the reading based on these general ranges relative to the selected time of day.
Use Cases for this Calculator
Self-Monitoring: Individuals with diabetes can use this to quickly get a general idea of their readings in context.
Awareness: People curious about their glucose levels can use it for informational purposes.
Educational Tool: Helps understand the typical ranges for blood sugar at different times.
Important Disclaimer
This calculator is an automated tool and cannot provide medical diagnoses or treatment plans. Blood sugar levels can be influenced by many factors, including diet, exercise, medication, stress, and illness. Always consult with your doctor or a qualified healthcare provider for any health concerns or before making any decisions related to your health or treatment. Never disregard professional medical advice or delay seeking it because of something you have read or interpreted using this calculator.
function calculateBloodSugar() {
var readingInput = document.getElementById("bloodSugarReading").value;
var unit = document.getElementById("unit").value;
var timeOfDay = document.getElementById("timeOfDay").value;
var resultValueElement = document.getElementById("result-value");
var resultCategoryElement = document.getElementById("result-category");
var interpretationElement = document.getElementById("interpretation");
resultValueElement.innerText = "–";
resultCategoryElement.innerText = "–";
interpretationElement.innerText = "";
var reading = parseFloat(readingInput);
if (isNaN(reading) || reading <= 0) {
resultCategoryElement.innerText = "Invalid Input";
interpretationElement.innerText = "Please enter a valid positive number for your blood sugar reading.";
return;
}
var reading_mg_dL;
var reading_mmol_L;
// Convert to a standard unit (mg/dL) for easier comparison
if (unit === "mmol/L") {
reading_mmol_L = reading;
reading_mg_dL = reading * 18.018;
} else {
reading_mg_dL = reading;
reading_mmol_L = reading / 18.018;
}
var category = "";
var interpretation = "";
var targetRange = "";
// Define target ranges (these are general guidelines and may vary)
var fasting_target_mg_dL = { low: 70, high: 99 }; // Non-diabetic
var fasting_target_diabetic_mg_dL = { low: 80, high: 130 }; // Diabetic target
var post_meal_2hr_target_mg_dL = { low: null, high: 140 }; // Non-diabetic
var post_meal_2hr_target_diabetic_mg_dL = { low: null, high: 180 }; // Diabetic target
var hypoglycemia_threshold_mg_dL = 70;
var hyperglycemia_threshold_mg_dL = 180; // General high threshold after meal
var displayReading = reading_mg_dL.toFixed(1);
var displayUnit = "mg/dL";
// Determine category and interpretation based on time of day and reading
if (timeOfDay === "fasting") {
targetRange = `${fasting_target_mg_dL.low}-${fasting_target_mg_dL.high} mg/dL (Non-Diabetic) / ${fasting_target_diabetic_mg_dL.low}-${fasting_target_diabetic_mg_dL.high} mg/dL (Diabetic Target)`;
if (reading_mg_dL = fasting_target_mg_dL.low && reading_mg_dL = fasting_target_diabetic_mg_dL.low && reading_mg_dL fasting_target_diabetic_mg_dL.high) {
category = "Hyperglycemia (High)";
interpretation = "Your fasting blood sugar is above the recommended target ranges. This could indicate hyperglycemia. Please consult your doctor.";
} else {
// Fallback for readings between normal non-diabetic and diabetic target low
category = "Slightly Elevated / Borderline";
interpretation = "Your fasting blood sugar is slightly above the normal non-diabetic range but may be within target for some diabetic individuals. Discuss with your doctor.";
}
} else if (timeOfDay === "postMeal2hr") {
targetRange = `< ${post_meal_2hr_target_mg_dL.high} mg/dL (Non-Diabetic) / < ${post_meal_2hr_target_diabetic_mg_dL.high} mg/dL (Diabetic Target)`;
if (reading_mg_dL < hypoglycemia_threshold_mg_dL) {
category = "Hypoglycemia (Low)";
interpretation = "Your blood sugar level 2 hours after a meal is very low. This requires attention. Please consult your doctor.";
} else if (reading_mg_dL < post_meal_2hr_target_mg_dL.high) {
category = "Normal (Post-Meal)";
interpretation = "Your blood sugar level 2 hours after a meal is within the typical normal range for non-diabetic individuals.";
} else if (reading_mg_dL <= post_meal_2hr_target_diabetic_mg_dL.high) {
category = "Within Diabetic Target Range (Post-Meal)";
interpretation = "Your blood sugar level 2 hours after a meal is within the target range for many individuals managing diabetes.";
} else {
category = "Hyperglycemia (High)";
interpretation = "Your blood sugar level 2 hours after a meal is above the recommended target. This could indicate hyperglycemia. Please consult your doctor.";
}
} else if (timeOfDay === "postMeal1hr") {
// 1 hour after meal is typically higher than 2 hours. Ranges are wider.
// General guideline: < 180 mg/dL (10.0 mmol/L) for non-diabetics, < 200 mg/dL (11.1 mmol/L) for diabetics
var post_meal_1hr_target_mg_dL = { low: null, high: 180 }; // Non-diabetic
var post_meal_1hr_target_diabetic_mg_dL = { low: null, high: 200 }; // Diabetic target
targetRange = `< ${post_meal_1hr_target_mg_dL.high} mg/dL (Non-Diabetic) / < ${post_meal_1hr_target_diabetic_mg_dL.high} mg/dL (Diabetic Target)`;
if (reading_mg_dL < hypoglycemia_threshold_mg_dL) {
category = "Hypoglycemia (Low)";
interpretation = "Your blood sugar level 1 hour after a meal is very low. This requires attention. Please consult your doctor.";
} else if (reading_mg_dL <= post_meal_1hr_target_mg_dL.high) {
category = "Normal (Post-Meal)";
interpretation = "Your blood sugar level 1 hour after a meal is within the typical normal range for non-diabetic individuals.";
} else if (reading_mg_dL <= post_meal_1hr_target_diabetic_mg_dL.high) {
category = "Within Diabetic Target Range (Post-Meal)";
interpretation = "Your blood sugar level 1 hour after a meal is within the target range for many individuals managing diabetes.";
} else {
category = "Hyperglycemia (High)";
interpretation = "Your blood sugar level 1 hour after a meal is above the recommended target. This could indicate hyperglycemia. Please consult your doctor.";
}
} else if (timeOfDay === "bedtime") {
// Bedtime ranges are similar to fasting, often slightly higher target range to prevent overnight lows.
// e.g., 100-140 mg/dL (5.6-7.8 mmol/L) for diabetics
var bedtime_target_diabetic_mg_dL = { low: 100, high: 140 };
targetRange = `Approx. 100-140 mg/dL (Diabetic Target)`; // Simplified general range
if (reading_mg_dL = bedtime_target_diabetic_mg_dL.low && reading_mg_dL bedtime_target_diabetic_mg_dL.high) {
category = "Hyperglycemia (High)";
interpretation = "Your bedtime blood sugar is higher than typically recommended. Consult your doctor.";
} else {
category = "Borderline / Needs Monitoring";
interpretation = "Your bedtime blood sugar is below the typical diabetic target range but above hypoglycemia levels. Monitor closely and discuss with your doctor.";
}
}
else { // anytime
if (reading_mg_dL hyperglycemia_threshold_mg_dL) {
category = "Hyperglycemia (High)";
interpretation = "This reading is high. Consistent high readings may indicate hyperglycemia. Consult your doctor for diagnosis and management.";
} else {
category = "Within General Range";
interpretation = "This reading falls within a generally acceptable range, but context (like time of day relative to meals) is important for a full interpretation. Consult your healthcare provider for personalized guidance.";
}
targetRange = `General guideline: 70-180 mg/dL (0-2 hours post-meal)`;
}
resultValueElement.innerText = `${displayReading} ${displayUnit}`;
resultCategoryElement.innerText = category;
interpretationElement.innerHTML = `Interpretation: ${interpretation}(General Target Range: ${targetRange})`;
}