Carb counting

Diabetes Nurse Educator, Christine Manga, helps us understand the need for carb counting if you have diabetes.

What is carb counting?

Carbohydrate (carb) counting is a meal management tool for people with both Type 1 and Type 2 diabetes who use insulin. The aim of carb counting is to balance the mealtime insulin injected with the amount of carbs eaten at each meal. Insulin is the hormone responsible for getting sugar from the blood stream into the cells where it can be used. So by carb counting, you will have better glucose control and more meal flexibility.

What are carbs?

Carbohydrates is the nutrient that affects your blood glucose the most. They are one of the main nutrients found in food. The other main nutrients are fat and protein.

Carbohydrates are found in starches and sugars. There are healthy and unhealthy carbs. Healthy carbs include whole grains, vegetables and fruit. These carbs contain energy, and nutrients, such as fibre, vitamins and minerals.

Unhealthy carbs are food and drinks containing added sugars. These foods are often energy dense but have low amounts of nutrients.

Carb exchange

A ‘carb’ or ‘carb exchange’ is a portion of food that contains 15 grams of carbohydrates. In order to carb count, you’ll need to know what foods contain carbohydrates. The following foods contain carbohydrates:

  • Rice, pasta, oatmeal, corn and grains.
  • Breads, cereals, biscuits and crackers.
  • Most snack foods.
  • Dried beans and lentils.
  • Starchy vegetables, such as potatoes, sweet corn, peas and sweet potatoes.
  • Fruit – both fresh and dried as well as fruit juice.
  • Dairy products including milk and yoghurt.
  • Honey, syrup, sugar, sweets and desserts.

Generally speaking, a ‘carb’ is:

  • ½ a cup of cooked rice, pasta, oats, pap, beans or lentils.
  • ½ a cup of cooked starchy vegetables like potatoes, peas, corn or a mealie.
  • ½ a hamburger or hotdog roll, one slice of bread, one small tortilla.
  • 2 cups of popcorn.
  • 3/4 cup of breakfast cereal.
  • ¼ cup of muesli. It is best to read the label for this type of cereal as some contain more dried fruit than others.
  • 1 small to medium fresh fruit (about a handful).
  • ½ cup of fruit juice.
  • ¼ cup dried fruit.
  • 1 cup of milk.
  • 100ml flavoured yoghurt.

Read food labels

To get the exact carb content of a food, you will need to read the nutritional label. Carbohydrates will be measured per 100g and per serving size. Weighing your food may be necessary as you get used to portion sizes. It is important to count the carbs for your full portion.

Apart from food labels, other sources of nutritional information can be found at or book South African Glycaemic Index and Load Guide book by Liesbet Delport and Gabi Steenkamp is also helpful.

How many carbs should you have a day?

You can average on 30-60 grams per meal and 15 grams for two snacks a day. This would be adjusted according to sex, activity levels, weight goals and personal preferences.

Carb/insulin ratio

To find out how much insulin you would need for 15 grams of carbs to be transported into your cells (carb/insulin ratio), visit your doctor or educator.

This ratio is calculated on your total daily dose of all insulins you use. It will change if the amount of insulin you are using increases or decreases drastically.

Carb counting will seem tedious initially, but with time and practice you will also gain experience-based estimation that will guide you.

Christine Manga (Post Grad Dip Diabetes and Msc Diabetes) is a professional nurse and a diabetes nurse educator. She has worked with Dr Angela Murphy at CDE Centre, Sunward Park since 2012.


Christine Manga (Post Grad Dip Diabetes and Msc Diabetes) is a professional nurse and a diabetes nurse educator. She has worked with Dr Angela Murphy at CDE Centre, Sunward Park since 2012.