What is a metabolic disease?
Metabolism means all the changes in your body that turn food into energy and body parts. A metabolic disease is when something goes wrong in these changes. The cause can be a missing hormone, a weak enzyme, or a body that is out of balance because of food and lifestyle.
Examples: diabetes (sugar), obesity (too much stored fat), high cholesterol (too much fat in blood) and gout (too much uric acid).
Blood sugar and insulin
Glucose is the sugar that cells burn for energy. After a meal it enters the blood. The pancreas then releases the hormone insulin. Insulin tells muscle, liver and fat cells to take glucose in. Extra glucose is stored as glycogen in the liver and muscles. So blood sugar comes down.
If blood sugar falls too low, another hormone, glucagon, tells the liver to release glucose. Two hormones, one balance.
Normal fasting blood sugar is about 70 to 100 mg/dL (3.9 to 5.6 mmol/L).
Diabetes: type 1 and type 2
Diabetes mellitus means blood sugar stays too high for a long time.
- Type 1: the body's own defence system damages the insulin-making cells of the pancreas. Little or no insulin is made. It often starts in children and young people. Treatment is insulin injections or a pump.
- Type 2: the cells become insulin resistant, so insulin works badly. It is linked to extra body fat, little exercise, age and family history. Treatment is food, exercise, tablets and sometimes insulin.
Another form, gestational diabetes, can appear during pregnancy.
Signs, risks and prevention
Common signs: very thirsty, passing urine often, always hungry, tired, slow-healing cuts, blurry sight.
Long-term harm if sugar stays high: damage to eyes, kidneys, nerves, heart and blood vessels.
Keeping safe: eat less sugary food and drink, eat more vegetables, whole grains and pulses, move for 30 minutes a day, keep a healthy weight, and get a blood test if you have signs or family history. Only a doctor can diagnose diabetes.
Try it
In the 3D, set Cell response to 100 and raise Insulin: watch the doors open and the tower fall. Now set Insulin to 0 (type 1). Then set Insulin high but Cell response low (type 2). Predict the tower first, then check. At home, compare two days: a walk after dinner, or no walk. Ask an adult to note how you feel, not to measure anything.
Key formulas and definitions
- Normal fasting blood glucose: 70 to 100 mg/dL (3.9 to 5.6 mmol/L)
- Insulin (lowers blood sugar) and glucagon (raises it) work as a pair
- Type 1: too little insulin. Type 2: cells resist insulin
- BMI = weight (kg) / height² (m²)
Worked examples
1. Which hormone lowers blood sugar and which raises it?
Insulin lowers it by moving glucose into cells and storing it as glycogen. Glucagon raises it by making the liver release glucose.
2. A person has blood sugar of 160 mg/dL before breakfast, on two tests. Is this in the normal range?
No. Normal fasting sugar is about 70 to 100 mg/dL. 160 is high. The person should see a doctor for a proper check.
3. A 14-year-old girl suddenly gets very thirsty, passes urine often and loses weight. Insulin injections help her. Which type is likely?
Type 1. It starts young, the pancreas makes little insulin, and insulin injections are the treatment.
Common mistakes
- Thinking diabetes is caused only by eating sweets. Body weight, exercise, family history and age matter too.
- Mixing glucose, glycogen and glucagon. Glucose is the sugar, glycogen is the stored form, glucagon is the hormone.
- Saying type 2 means no insulin. Insulin is often present but cells do not respond well.
- Believing diabetes is catching like a cold. It is not infectious.