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Trouble-Shooting High Blood Glucose Levels (for people with Type 1 Diabetes)


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Despite meticulous management, blood glucose levels can occasionally rise. While the Insulin Sensitivity Factor (ISF) can temporarily correct high readings, identifying and addressing the underlying causes is crucial. 


1. Decreased insulin sensitivity  

Possible reasons include illness*, reduced physical activity, pre-menstrual hormonal changes or new medications such as traditional medications or steroids. 

*It is important to have an individualised sick day management plan. If you feel unwell with blood glucose levels persistently over 14 mmol/L, refer to your plan. 

 2. Missed or delayed insulin doses (For example, administering quick-acting insulin post-meal instead of pre-meal, or delaying basal insulin injections)  

3. Insufficient basal insulin doses 

4. Insufficient quick-acting insulin for meal carbohydrates  

This may result from an incorrect insulin-to-carbohydrate ratio (ICR) or underestimating carbohydrate content in meals. 

5. Injecting insulin into lumpy or lipohypertrophic sites 

6. Expired or spoilt insulin (For example, insulin exposed to high temperatures, like in a car under the sun, may become ineffective.)  


Starting the day with a favourable pre-breakfast glucose level can positively influence the rest of your day.  

If you consistently have high readings upon waking, consider discussing the following with your healthcare team: 

  • High bedtime glucose levels (post-dinner readings): This may be due to insufficient quick-acting insulin for dinner, excessive carbohydrate intake or a high-fat dinner. 
  • Supper: Depending on the carbohydrate content of your supper, you might need quick-acting insulin. Consult your healthcare team for management strategies. 
  • Nocturnal hypoglycaemia: Leading to rebound hyperclycaemia in the morning 
  • Insufficient basal insulin 
  • Dawn phenomenon 
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