Overview

This information gives advice about diet for people who have a condition called reactive hypoglycaemia.

Reactive hypoglycaemia is when you have a low blood sugar level after eating. This usually happens 2 to 5 hours after a meal in people with diabetes. It is different from low blood sugar (hypoglycaemia) that happens while fasting.

In most cases, it is not known why reactive hypoglycaemia happens. Your pancreas (a gland behind the stomach) makes a hormone (chemical substance) called insulin, which lowers blood sugar levels. The condition is thought to be caused by your body either:

• making too much insulin after you have food or drink that is high in carbohydrate
• being oversensitive to insulin or other hormones that help to control your blood sugar levels

If you have any more questions or concerns about reactive hypoglycaemia, please speak to your dietitian or healthcare professional.

Symptoms of reactive hypoglycaemia

Common symptoms of reactive hypoglycaemia include:

• dizziness or light-headedness
• extreme hunger or appetite
• difficulty concentrating
• sweating
• rapid heartbeat
• tingling lips
• trembling
• blurred eyesight

Treating the symptoms of reactive hypoglycaemia

If you have symptoms of reactive hypoglycaemia, you need to follow these steps immediately.

1. Have a sugary drink or snack. A suitable drink is a small 150 to 200ml glass of non-diet fizzy drink or fruit juice. A suitable snack is 15 to 20g of a fast-acting carbohydrate. Examples are 3 to 4 jelly babies, 4 to 6 glucose tablets or 1 tube of glucose gel.
2. Test your blood sugar level after 10 to 15 minutes. If it has improved and you feel better, move to step 3. But if there is little or no change, have another sugary drink or snack. Measure your blood sugar level again after 10 to 15 minutes.
3. You need to prevent your blood sugar level from dropping again. Eat your next meal if it is due and contains a starchy carbohydrate, such as bread, pasta, potato or rice. Otherwise, have a snack that contains a slow-release carbohydrate. Examples are a slice of bread or toast, 2 digestive biscuits or a glass of cows’ milk.

Diagnosing reactive hypoglycaemia

We use an oral glucose tolerance test to diagnose reactive hypoglycaemia. You usually have this test at the hospital. It involves:

• having a sugary (glucose) drink
• monitoring your blood sugar level to see how your body reacts to carbohydrate

If you have reactive hypoglycaemia, this is mainly managed through your diet. You might be referred to a dietitian for personalised advice.

Preventing reactive hypoglycaemia

Managing your diet is usually the best way to prevent reactive hypoglycaemia. It is also helpful to keep to a healthy body weight and do regular moderate intensity exercise. This is any activity that raises your heart rate, and makes you breathe faster and feel warmer.

If you continue to have reactive hypoglycaemia frequently after following the guidelines in this section, please see your GP or consultant.

By making the following changes to your diet, you can help to relieve your symptoms.

Have regular meals

It is best to:

• eat 3 meals a day with a small snack between each meal
• eat about every 3 hours to avoid long gaps between meals

Eat a balanced diet

A balanced diet includes a variety of foods and at least 5 portions of fruit and vegetables every day. In each meal, try to include:

• some vegetables, salad or fruit to give you fibre
• wholegrain starchy foods, such as wholewheat pasta, brown rice or potatoes with their skin on, which are also high in fibre
• a protein food, such as meat, fish, egg, beans, lentils, nuts or tofu

Adding a portion of healthy (unsaturated) fats, such as olive oil, nuts, seeds or avocado, can slow down the digestion of carbohydrate. This can reduce your chance of getting reactive hypoglycaemia.

The NHS website has more information about how to eat healthy, balanced meals.

Avoid large portions of starchy carbohydrates

Large amounts of starchy carbohydrates can raise your blood sugar levels and keep them high. Examples include:

• rice
• bread
• potatoes
• yams
• pasta
• chapattis

Instead, have a small to medium portion with each meal and space these foods out throughout the day.

Choose low glycaemic index (GI) foods

Low glycaemic index (GI) foods are less processed and often high in fibre. Your body breaks down (digests) these foods more steadily and they release sugar at a slower rate. This means that your blood sugar levels rise more gradually over time.

Examples of low GI foods include:

• wholegrain breads
• rye bread
• oats
• beans
• lentils
• most fresh fruit (but not fruit juices or dried fruit)
• sweet potato
• brown or basmati rice
• oats
• yoghurt

Limit sugar, alcohol and caffeine

Try to avoid eating too many sugary foods, such as:

• cakes
• biscuits
• chocolate
• ice cream
• puddings
• jam

You can sometimes eat a small amount of these foods after a meal.

It’s also important to avoid sugar and sugary drinks because they can lead to reactive hypoglycaemia. Examples include:

• sugar that you add to food or drinks, honey, jellies and sweets
• energy drinks, sugary fizzy drinks, soft drinks, fruit juices, smoothies and hot chocolate

Alcohol can lower your blood sugar levels. Here are some tips if you do drink alcohol.

Coffee, tea and some soft drinks contain caffeine. This can make the symptoms of reactive hypoglycaemia worse. It is best to choose decaffeinated coffee or tea and diet soft drinks, which have most caffeine removed.