Use this calculator to understand what your blood glucose reading might indicate based on the time of measurement and unit used. Remember, this tool provides general information and is not a substitute for professional medical advice.
mg/dL
mmol/L
Fasting (8+ hours without food)
Before a Meal
2 Hours After a Meal
Anytime / Random
Bedtime
function calculateBloodSugar() {
var glucoseValueInput = document.getElementById("glucoseValue");
var glucoseUnit = document.getElementById("glucoseUnit").value;
var readingTime = document.getElementById("readingTime").value;
var resultDiv = document.getElementById("result");
var glucoseValue = parseFloat(glucoseValueInput.value);
if (isNaN(glucoseValue) || glucoseValue <= 0) {
resultDiv.innerHTML = "Please enter a valid positive blood glucose reading.";
return;
}
var glucoseMgdL; // Value converted to mg/dL for internal comparison
var glucoseMmolL; // Value converted to mmol/L for internal comparison
// Convert to mg/dL if input is mmol/L, otherwise use as is
if (glucoseUnit === "mmolL") {
glucoseMgdL = glucoseValue * 18;
glucoseMmolL = glucoseValue;
} else { // mg/dL
glucoseMgdL = glucoseValue;
glucoseMmolL = glucoseValue / 18;
}
var interpretation = "";
var recommendation = "";
var statusClass = ""; // For styling (e.g., normal, warning, danger)
// Define ranges (in mg/dL)
var ranges = {
fasting: {
hypo: { upper: 70, text: "Hypoglycemia (low blood sugar)" },
normal: { lower: 70, upper: 99, text: "Normal" },
prediabetes: { lower: 100, upper: 125, text: "Prediabetes" },
diabetes: { lower: 126, text: "Diabetes" }
},
beforeMeal: {
hypo: { upper: 70, text: "Hypoglycemia (low blood sugar)" },
targetLow: { lower: 80, upper: 130, text: "Within Target Range (for many with diabetes)" },
high: { lower: 131, text: "Elevated (potentially high)" }
},
afterMeal: { // 2 Hours Postprandial
hypo: { upper: 70, text: "Hypoglycemia (low blood sugar)" },
normal: { lower: 70, upper: 139, text: "Normal" },
prediabetes: { lower: 140, upper: 199, text: "Prediabetes" },
diabetes: { lower: 200, text: "Diabetes" }
},
anytime: { // Random
hypo: { upper: 70, text: "Hypoglycemia (low blood sugar)" },
normal: { lower: 70, upper: 199, text: "Normal (without symptoms)" },
diabetes: { lower: 200, text: "Diabetes (especially with symptoms)" }
},
bedtime: {
hypo: { upper: 70, text: "Hypoglycemia (low blood sugar)" },
targetLow: { lower: 100, upper: 140, text: "Within Target Range (for many with diabetes)" },
high: { lower: 141, text: "Elevated (potentially high)" }
}
};
var currentRanges = ranges[readingTime];
if (glucoseMgdL = currentRanges.diabetes.lower) {
interpretation = currentRanges.diabetes.text;
recommendation = "This level indicates potential diabetes. Consult a healthcare professional for diagnosis and management.";
statusClass = "danger";
} else if (glucoseMgdL >= currentRanges.prediabetes.lower) {
interpretation = currentRanges.prediabetes.text;
recommendation = "This level suggests prediabetes. Lifestyle changes (diet, exercise) are crucial. Consult a doctor.";
statusClass = "warning";
} else { // Normal fasting
interpretation = currentRanges.normal.text;
recommendation = "Your fasting blood sugar is within the normal range. Continue healthy habits.";
statusClass = "normal";
}
} else if (readingTime === "afterMeal") {
if (glucoseMgdL >= currentRanges.diabetes.lower) {
interpretation = currentRanges.diabetes.text;
recommendation = "This level indicates potential diabetes. Consult a healthcare professional for diagnosis and management.";
statusClass = "danger";
} else if (glucoseMgdL >= currentRanges.prediabetes.lower) {
interpretation = currentRanges.prediabetes.text;
recommendation = "This level suggests prediabetes. Lifestyle changes (diet, exercise) are crucial. Consult a doctor.";
statusClass = "warning";
} else { // Normal after meal
interpretation = currentRanges.normal.text;
recommendation = "Your blood sugar 2 hours after a meal is within the normal range. Continue healthy habits.";
statusClass = "normal";
}
} else if (readingTime === "anytime") {
if (glucoseMgdL >= currentRanges.diabetes.lower) {
interpretation = currentRanges.diabetes.text;
recommendation = "This random level, especially if accompanied by symptoms like increased thirst, frequent urination, or unexplained weight loss, strongly suggests diabetes. Consult a healthcare professional immediately.";
statusClass = "danger";
} else { // Normal random
interpretation = currentRanges.normal.text;
recommendation = "Your random blood sugar is within a typical range. If you have concerns or symptoms, consult a doctor.";
statusClass = "normal";
}
} else if (readingTime === "beforeMeal" || readingTime === "bedtime") {
if (glucoseMgdL >= currentRanges.high.lower) {
interpretation = currentRanges.high.text;
recommendation = "This level is elevated. If you have diabetes, this is above the typical target range. Consult your doctor or diabetes educator for advice on managing your blood sugar.";
statusClass = "warning";
} else if (glucoseMgdL >= currentRanges.targetLow.lower && glucoseMgdL <= currentRanges.targetLow.upper) {
interpretation = currentRanges.targetLow.text;
recommendation = "This level is within the typical target range for many individuals with diabetes. Continue to follow your management plan.";
statusClass = "normal";
} else { // Below target but not hypoglycemic
interpretation = "Below Target Range (for many with diabetes)";
recommendation = "This level is below the typical target range for many individuals with diabetes, but not yet hypoglycemic. Monitor closely and consult your doctor if this is a frequent occurrence.";
statusClass = "warning";
}
}
var equivalentValue = "";
if (glucoseUnit === "mmolL") {
equivalentValue = " (" + glucoseMgdL.toFixed(1) + " mg/dL)";
} else {
equivalentValue = " (" + glucoseMmolL.toFixed(1) + " mmol/L)";
}
resultDiv.innerHTML =
"Your Blood Glucose Reading: " + glucoseValue.toFixed(1) + " " + (glucoseUnit === "mgdl" ? "mg/dL" : "mmol/L") + equivalentValue + "" +
"Time of Reading: " + document.getElementById("readingTime").options[document.getElementById("readingTime").selectedIndex].text + "" +
"Interpretation: " + interpretation + "" +
"Recommendation: " + recommendation + "" +
"Disclaimer: This calculator provides general information and is not a substitute for professional medical advice. Always consult with a healthcare provider for diagnosis and treatment.";
}
.calculator-container {
background-color: #f9f9f9;
border: 1px solid #ddd;
padding: 20px;
border-radius: 8px;
max-width: 600px;
margin: 20px auto;
font-family: Arial, sans-serif;
box-shadow: 0 2px 4px rgba(0,0,0,0.1);
}
.calculator-container h2 {
color: #333;
text-align: center;
margin-bottom: 20px;
font-size: 1.8em;
}
.calculator-container p {
color: #666;
line-height: 1.6;
margin-bottom: 15px;
}
.form-group {
margin-bottom: 15px;
}
.form-group label {
display: block;
margin-bottom: 5px;
font-weight: bold;
color: #555;
}
.form-group input[type="number"],
.form-group select {
width: calc(100% – 22px);
padding: 10px;
border: 1px solid #ccc;
border-radius: 4px;
font-size: 16px;
box-sizing: border-box;
}
.calculator-container button {
background-color: #28a745; /* Green button */
color: white;
padding: 12px 20px;
border: none;
border-radius: 4px;
cursor: pointer;
font-size: 18px;
width: 100%;
margin-top: 10px;
transition: background-color 0.3s ease;
}
.calculator-container button:hover {
background-color: #218838; /* Darker green on hover */
}
.calculator-result {
margin-top: 25px;
padding: 15px;
border: 1px solid #e0e0e0;
border-radius: 4px;
background-color: #eaf7ed; /* Light green background for results */
box-shadow: inset 0 1px 3px rgba(0,0,0,0.05);
}
.calculator-result p {
margin-bottom: 8px;
line-height: 1.5;
color: #333;
}
.calculator-result p:last-child {
margin-bottom: 0;
}
.calculator-result .normal {
color: #28a745; /* Green for normal */
font-weight: bold;
}
.calculator-result .warning {
color: #ffc107; /* Yellow for warning */
font-weight: bold;
}
.calculator-result .danger {
color: #dc3545; /* Red for danger */
font-weight: bold;
}
.calculator-result .error {
color: #dc3545;
font-weight: bold;
}
.calculator-result .disclaimer {
font-size: 0.9em;
color: #6c757d;
margin-top: 15px;
border-top: 1px dashed #ccc;
padding-top: 10px;
}
Understanding Your Blood Sugar Levels
Blood sugar, or blood glucose, is the main sugar found in your blood. It comes from the food you eat and is your body's primary source of energy. Your blood carries glucose to all the body's cells to be used for energy. Maintaining healthy blood sugar levels is crucial for overall health, as consistently high or low levels can lead to serious health complications.
Why Monitor Blood Sugar?
Monitoring blood sugar is essential for several reasons:
Diabetes Management: For individuals with diabetes, regular monitoring helps manage the condition, prevent complications, and adjust medication, diet, and exercise plans.
Prediabetes Awareness: If you have prediabetes, tracking your levels can motivate lifestyle changes to prevent progression to type 2 diabetes.
General Health: Even without diabetes, understanding your blood sugar patterns can help you make informed dietary and lifestyle choices for better energy and long-term health.
Units of Measurement: mg/dL vs. mmol/L
Blood glucose levels are measured in two primary units:
Milligrams per deciliter (mg/dL): This unit is commonly used in the United States and some other countries.
Millimoles per liter (mmol/L): This unit is prevalent in Canada, the UK, Australia, and many European countries.
The conversion factor between these units is approximately 18. To convert mmol/L to mg/dL, multiply by 18. To convert mg/dL to mmol/L, divide by 18. Our calculator handles this conversion for you.
Interpreting Your Readings: Context Matters
The meaning of your blood sugar reading depends heavily on when you take it. Here are the common contexts:
Fasting Blood Sugar: Taken after not eating or drinking anything (except water) for at least 8 hours, usually first thing in the morning.
Before a Meal (Pre-meal): Taken just before you eat. For people with diabetes, this helps determine if insulin or medication adjustments are needed.
2 Hours After a Meal (Postprandial): Taken exactly two hours after the start of a meal. This shows how your body processes carbohydrates.
Anytime / Random Blood Sugar: Taken at any time of day, regardless of when you last ate.
Bedtime Blood Sugar: Taken before going to sleep, important for preventing overnight hypoglycemia or hyperglycemia.
What Do the Numbers Mean? (General Guidelines)
Here are general ranges for adults. These can vary based on individual health conditions, age, and specific medical advice. Always consult your doctor for personalized targets.
Fasting Plasma Glucose (FPG)
Normal: Less than 100 mg/dL (5.6 mmol/L)
Prediabetes: 100-125 mg/dL (5.6-6.9 mmol/L)
Diabetes: 126 mg/dL (7.0 mmol/L) or higher
2 Hours Postprandial (After Meal)
Normal: Less than 140 mg/dL (7.8 mmol/L)
Prediabetes: 140-199 mg/dL (7.8-11.0 mmol/L)
Diabetes: 200 mg/dL (11.1 mmol/L) or higher
Anytime / Random Plasma Glucose
Normal: Generally less than 200 mg/dL (11.1 mmol/L) if you don't have symptoms of diabetes.
Diabetes: 200 mg/dL (11.1 mmol/L) or higher, especially when accompanied by symptoms like increased thirst, frequent urination, or unexplained weight loss.
Before Meal & Bedtime (Target Ranges for Many with Diabetes)
Before Meal: 80-130 mg/dL (4.4-7.2 mmol/L)
Bedtime: 100-140 mg/dL (5.6-7.8 mmol/L)
Understanding High and Low Blood Sugar
Hypoglycemia (Low Blood Sugar): Typically defined as blood sugar below 70 mg/dL (3.9 mmol/L). Symptoms can include shakiness, sweating, confusion, dizziness, and hunger. Severe hypoglycemia is a medical emergency.
Hyperglycemia (High Blood Sugar): Consistently high blood sugar levels. Symptoms can include increased thirst, frequent urination, fatigue, and blurred vision. Chronic hyperglycemia can lead to serious long-term complications affecting the heart, kidneys, nerves, and eyes.
How to Use the Calculator
Enter Your Reading: Input your blood glucose number into the "Blood Glucose Reading" field.
Select Unit: Choose whether your reading is in "mg/dL" or "mmol/L".
Choose Time of Reading: Select the context in which you took the reading (e.g., Fasting, 2 Hours After a Meal).
Interpret: Click "Interpret Blood Sugar" to see a general interpretation of your level and a recommendation.
Examples:
Example 1 (Fasting, Normal): If you enter 92 mg/dL and select "Fasting", the calculator will likely indicate "Normal" and recommend continuing healthy habits.
Example 2 (Fasting, Prediabetes): If you enter 115 mg/dL and select "Fasting", it will suggest "Prediabetes" and advise lifestyle changes and consulting a doctor.
Example 3 (2 Hours After Meal, Diabetes): If you enter 210 mg/dL and select "2 Hours After a Meal", it will indicate "Diabetes" and strongly recommend consulting a healthcare professional.
Example 4 (Hypoglycemia): If you enter 65 mg/dL and select "Anytime", it will flag "Hypoglycemia" and provide advice on immediate action and seeking medical attention.
Example 5 (Bedtime, Diabetic Target): If you enter 120 mg/dL and select "Bedtime", it will likely show "Within Target Range (for many with diabetes)" and advise continuing your management plan.
Disclaimer: This Blood Sugar Level Interpreter is for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis, or treatment. Always consult with a qualified healthcare provider for any health concerns or before making any decisions related to your health or treatment.