Unit Converter
Glucose
(Primary Blood Sugar – Essential Marker for Diabetes, Hypoglycemia & Metabolic Function)
Synonyms
- Blood glucose
- Plasma glucose
- Serum glucose
- Fasting blood sugar (FBS)
- Random blood sugar (RBS)
- Dextrose
Units of Measurement
- mmol/L
- µmol/L
- mg/dL
- mg/100 mL
- mg%
- mg/L
- µg/mL
Key Conversions
(Molecular Weight of Glucose = 180.16 g/mol)
1 mg/dL = 0.0555 mmol/L
1 mmol/L = 18 mg/dL
1 mg/L = 0.00555 mmol/L
1 µg/mL = 1 mg/L
mg/dL = mg% = mg/100 mL
1 mmol/L = 1000 µmol/L
Description
Glucose is the body’s main metabolic fuel, essential for:
- Brain function
- Red blood cell metabolism
- Muscle & organ energy
- Hormonal regulation (insulin, glucagon, cortisol, GH, catecholamines)
Blood glucose reflects the balance between:
- Intestinal absorption
- Hepatic glucose production
- Peripheral uptake via insulin
Glucose testing is the cornerstone of diagnosing and monitoring diabetes.
Physiological Role
Glucose homeostasis is controlled by:
Lowering Hormone
- Insulin → increases cellular uptake, glycogenesis, lipogenesis
Raising Hormones
- Glucagon
- Epinephrine
- Cortisol
- Growth hormone
Maintained tightly between 70–140 mg/dL in healthy individuals.
Clinical Significance
1. Hyperglycemia
Occurs in:
- Diabetes mellitus (Type 1 & 2)
- Gestational diabetes
- Steroid therapy
- Sepsis / critical illness
- Cushing’s syndrome
- Acromegaly
- Pancreatitis
- Hyperthyroidism
Symptoms
- Polyuria
- Polydipsia
- Blurred vision
- Weight loss
- Fatigue
- In severe cases → ketoacidosis or hyperosmolar crisis
2. Hypoglycemia
Blood glucose:
- <70 mg/dL = alert level
- <54 mg/dL = clinically significant
- <40 mg/dL = severe hypoglycemia
Causes
- Excess insulin
- Sulfonylureas
- Alcohol binges
- Insulinoma
- Adrenal failure
- Liver disease
- Infection in children
Symptoms
- Tremors
- Sweating
- Palpitations
- Confusion
- Seizures
- Coma
Reference Intervals
(ADA + WHO + Tietz 8E + Mayo)
Fasting Glucose
- Normal: 70–99 mg/dL (3.9–5.5 mmol/L)
- Prediabetes: 100–125 mg/dL (5.6–6.9 mmol/L)
- Diabetes: ≥126 mg/dL (≥7.0 mmol/L)
Random Glucose
- Normal: <200 mg/dL
- Diabetes: ≥200 mg/dL with symptoms
2-hr OGTT
- Normal: <140 mg/dL (7.8 mmol/L)
- Prediabetes: 140–199 mg/dL
- Diabetes: ≥200 mg/dL (11.1 mmol/L)
Neonatal Glucose
- First 24 hrs: 45–120 mg/dL
- Post 24 hrs: 60–140 mg/dL
Critical Values
- <40 mg/dL (severe hypoglycemia)
- >500 mg/dL (risk of hyperosmolar crisis)
Diagnostic Uses
1. Diagnose Diabetes (Primary Use)
According to ADA and WHO criteria:
- Fasting glucose
- OGTT
- Random glucose
- HbA1c corroboration
2. Monitoring Treatment
- Insulin therapy
- Oral antidiabetic drugs
- Lifestyle changes
3. Emergency Evaluation
- DKA
- HHS
- Hypoglycemia workup
4. Screening
- Pregnancy (GDM)
- High-risk adults
- Obesity & metabolic syndrome
5. Pediatric Disorders
- Congenital hyperinsulinism
- Ketotic hypoglycemia
- Endocrine disorders
Analytical Notes
- Plasma preferred over serum (glycolysis lowers glucose if delayed)
- Use fluoride oxalate tube if delayed processing
- Capillary glucose slightly higher than venous post-meal
- Point-of-care meters less accurate in anemia, shock, high triglycerides
Clinical Pearls
- OGTT is the most sensitive test for early diabetes.
- Stress hyperglycemia can mimic diabetes-repeat testing is essential.
- Persistent fasting glucose 100–125 mg/dL = prediabetes, requiring lifestyle therapy.
- Hypoglycemia should always be evaluated using Whipple’s triad.
- In pregnancy, even mild hyperglycemia increases fetal risk.
Interesting Fact
The first glucose test was developed in the 19th century using copper reduction chemistry (Benedict’s test), long before modern enzymatic analyzers.
References
- Tietz Clinical Chemistry & Molecular Diagnostics, 8th Edition - Carbohydrates & Diabetes.
- ADA Standards of Medical Care in Diabetes.
- WHO Diabetes Diagnostic Criteria.
- AACE/ACE Diabetes Guidelines.
- Mayo Clinic Laboratories - Glucose.
- ARUP Consult - Diabetes Testing.
- MedlinePlus / NIH - Blood Glucose Tests.