Understanding the glycaemic index

The glycaemic index is a measure of how quickly sugars are released into the bloodstream.

If you have gestational diabetes, you need to keep an eye on your fat content too. Fats do not contain carbohydrates, but they are very calorific, so if you need to manage your weight then it’s a good idea to keep your fat intake low.

Managing your blood glucose

Managing your blood glucose does not just mean cutting down on simple carbohydrates – it means having a better understanding of how complex carbohydrates work. Certain types of carbohydrate, especially highly processed foods, such as white bread, release their sugars very quickly.

By keeping glucose levels fairly constant, you are more likely to avoid dips in energy, which can lead to cravings for sugary foods and the temptation to go for bigger portions of food.

Low GI diet

A very restricted diet, is not recommended when you are pregnant. However, choosing low GI foods more often, watching your portions, and limiting the amount of high GI foods you eat, can help you to manage your blood glucose levels. 

As a general rule, you need to replace foods with a high glycaemic index (such as white bread and sugary foods) with foods with a low to medium glycaemic index, such as wholegrain bread, brown rice, pasta, pulses, fish or chicken.

The amount of carbohydrate you eat, and when you eat it, usually depends on several things, including how hungry you get, your blood glucose levels and your weight gain. You should aim to have at least 175g of carbohydrate per day.

I had plain Ready Brek for breakfast, then a piece of fruit mid-morning and at lunchtime just a sandwich and a yoghurt, and another piece of fruit in the afternoon. At tea time I’d have something like a baked potato with chilli but small portions. Gemma, mum of one

Managing your glucose levels without cutting out carbs

  • Spread your carbohydrate intake through the day.
  • If you treat your diabetes with insulin or tablets (not Metformin alone)check your blood glucose levels before going to bed.  If  your blood glucose reading is low, having a carbohydrate snack for supper can help reduce the risk of your blood glucose levels dropping overnightovernight.
  • Many women find carbs hard to tolerate at breakfast time. Try having breakfasts with smaller portions of carbs.
  • Choose carbs that are low GI.
Try some of our meal ideas here


  1. NHS Choices [ accessed April 2015] What is the glycaemic index? http://www.nhs.uk/chq/pages/1862.aspx?categoryid=51 Review date: 23/08/2015
  2.  NICE (2015) Diabetes in pregnancy: management of diabetes and its complications from preconception to the postnatal period, National Institute of Health and Care Excellence https://www.nice.org.uk/guidance/ng3
  3. Institute of Medicine (2007) Dietary Reference Intakes: Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. Washington, DC, National Academies Press, 2002 IN doi: 10.2337/dc07-S048 Diabetes Care January 2007 vol. 30 no. suppl 1 S48-S65


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Read more about a healthy diet for diabetes

Last reviewed on March 1st, 2015. Next review date March 1st, 2018.

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