How does Low GI food affect my blood sugar?

People with diabetes aim to minimize their time 'out of range' to reduce long term complications.

These charts demonstrate what happens to your blood sugars for three different types of food - Low GI, Normal GI and High GI food.

A high GI food is absorbed quickly and the sugar spikes your blood sugar upwards, sometimes resulting in a 'sugar rush' feeling.

The same insulin was given for 60 grams of carbohydrate, in 3 separate meals of each food GI type, and insulin was delivered at commencement of the meal. Our target BGL (and starting BGL) is 90 mg/dl (5 mmol/l), and our target range is 72mg/dl-180mg/dl (4-10mmol/l).

These charts are generated by the ManageBGL system, which helps you manage your diabetes better in real time, on your iPhone, iPad or PC. See exactly what your BGLs, Carbs and Insulin are doing right now, and predict BGLs 3 hours ahead. ManageBGL allows you to select 5 different food GI types, and also set your default GI type (useful if you are a low carb eater).

  Icon Scenario Example food Observations from charts below
  60g Low GI food Brown rice, brown bread, unprocessed cereal Your BGL stays within the target range for the entire time. The food takes longer to be absorbed, so the person feels full for longer.
  60g Normal GI food Wholemeal bread, fruit, milk Your BGL spends about 45 minutes out of range, as the rate the insulin is absorbed is slower than the rate the carbs are absorbed. Expect this to impact your A1C.
  60g High GI food Cake, biscuits Your BGL spends over an hour out of range, again, the rate the insulin is absorbed is slower than the rate the carbs are absorbed. Expect this to impact your A1C even more.


Eating Low GI food makes it much easier to keep your BGL in range, hence lowering your A1C.

Discuss this scenario

BGL BGL Profile (mmol/l)

Carbs Carb Profile (grams active at a given time)

Click the Legend buttons to show the raw data for the graphs below it.

The ManageBGL charting system predicts High and Lo BGLs and suggests corrective action.


Available scenarios:

How does Low GI food affect my blood sugar?
Calculating Correction Ratio
Calculating Carbohydrate Ratio
Should I inject before my meal?
Afreeza versus Humalog/Novolog/NovoRapid
Lucy thought she was Low
Undiagnosed versus diagnosed Type 2 diabetic
Diabetes and Blindness

Suggestions for more scenarios? Please send them to us