Understanding carbohydrates

Understand the different types of carbohydrate and how they affect people with diabetes

Understanding how carbohydrate affects your blood sugar is an important step in managing your diabetes. Diabetes specialist dietitian and best selling author Chris Cheyette explains different types of carbohydrate, with advice on how to manage your blood sugar levels.

Carbohydrate comes in different forms. All the carbohydrate you eat gets turned into glucose, which the body uses for energy. As well as providing energy, carbohydrate is a key source of fibre, B-vitamins and minerals. For people with diabetes, and on tablets or insulin, it can also help to prevent hypoglycemia (low blood glucose).

How much carbohydrate should I eat?

Many clients often ask me how much carbohydrate they should be eating on a daily basis. While I would like to be able to give them a clear answer, the truth is that there is currently no consensus among scientists about what the daily amount for men and women should be. It would seem that the amount required is likely to vary from person to person, and is probably affected by a range of factors, such as age, activity levels, diabetes medication and diet.

When trying to manage day-to-day blood glucose levels it is important to consider the total amount of carbohydrate in each meal and snack, as this is what determines what will happen to the blood glucose - the more carbohydrate, the more the blood glucose will rise. People with Type 1 diabetes are usually taught to adjust their insulin based on the carbohydrate in that meal. For those with Type 2 diabetes it is useful to have an understanding about the carbohydrate content in the food so they can avoid large amounts at once, which are likely to make the blood glucose rise beyond normal levels.

Types of Carbohydrate

There are 2 main types of carbohydrate; starchy carbohydrates and sugars.

Starchy carbohydrates

Starchy carbohydrates include foods such as bread, pasta, rice, potato, lentils, and cereal.

Are they all the same?

No. Ideally you should try to choose wholegrain and unprocessed varieties e.g. wholegrain bread and porridge oats as these cause a slower increase in blood glucose.


Natural sugars

Many foods contains natural sugars (such as fructose and lactose) and these are normally combined with fibre, vitamins and minerals, which are beneficial to our health. The sugar in these foods gets into the blood more slowly than added sugar. These slower releasing sugars have a lower GI and are therefore better for you. You can find natural sugar in foods such as fresh and dried fruit (fructose), milk and yoghurts (lactose).

Added sugars

Other sugars such as ‘added sugars’ go into foods during processing or when you prepare them at home. Added sugar means additional calories and extra carbohydrate, which can increase the blood glucose after you eat or drink that food. So if you’re trying to lose weight and control your diabetes it’s a good idea to limit the added sugars in your diet or swap to a low calorie sweetener like SPLENDA®.

Glycaemic Index (GI)

GI is a measure of how quickly carbohydrate foods make the blood glucose rise. Foods that have the highest GI cause the most rapid rise. Sugar, white bread and sugary drinks are all examples of high GI foods. Ideally people with Type 2 diabetes should choose low GI foods as often as possible. These include wholegrain cereals and breads, fruit and vegetables, brown rice, wholewheat pasta and milk.