Studies have shown that dietary fat and protein can result in postprandial hyperglycemia in patients with type 1 diabetes. Meals high in fat and protein may require additional insulin delivered over several hours.
Protein intake in healthy individuals does not raise blood glucose. Insulin secretion is stimulated for amino acid uptake and glucagon is secreted to maintain euglyemia. In diabetes, protein intake may impact glycemia via the hormones glucagon, cortisol, GH, IGF-1, and ghrelin as well as through gluconeogenesis of amino acids to glucose.
In diabetes, protein intake can:
- Lead to a delayed rise in blood glucose ~100 minutes
- Have different glycemic effects depending on whether ingested with CHO or alone
- 30g protein with CHO can affect blood glucose BUT
- > 75 g protein may be required to affect blood glucose if eaten alone, without carbohydrate
FatFat intake in healthy indviduals results in:
- Delayed gastric emptying
- Increased glucose-stimulated insulin secretion in beta cells from FFA
- Altered release of hormones (glucagon, GLP-1, GIP, ghrelin)
- Gluconeogenesis of some glycerol into glucose (small impact)
- Reduce early glucose response (first 2-3 hours)
- Delay peak blood glucose due to delayed gastric emptying
- Lead to late postprandial hyperglycemia (>3 hours – as long as 8 hours in some studies)
- In some cases double insulin requirements (50 g fat)
Optimal dosing strategies for protein and/or fats is not known due to the limited studies available, the quality of the studies and the small number of patients in each. It's also important to note there are significant inter-individual glycemic effects of proteins and fat. The methods below are simply a starting point and personalized adjustments must be made based on glucose responses. It is expected other formulas and tools will emerge over time.
Before adjusting insulin dose for the fat and protein content of meals, it is important to first assist patients in optimizing their basal rates, carbohydrate counting, insulin-to-carbohydrate ratios as well as their treatment and prevention of hypoglycemia. Then, if ingestion of high fat and/or high protein meals is associated with delayed hyperglycemia the methods below could assist in calculating and administering extra insulin. Ensure patients demonstrate comfort and competency in the required math, which may include the use of calories and/or grams of protein and fat.
Method A: Percent Increase and Dual Boluses
If eating > 40 g fat and > 25 g protein with a carbohydrate (CHO) meal increase the calculated ICR meal dose by 30-35%
- For insulin pump: deliver 50% of this new dose (usual dose + the increase) as a normal pre-meal bolus and 50% as square/extended wave over 2 - 2.5 hours
- For MDI: administer 50% of this new dose (usual dose + the increase) as pre-meal bolus and 50% as post-meal bolus 1 - 1.5 hours after the meal.
Assess the glycemic response and adjust the following as required:
- The pre-meal bolus:post-meal ratio ( 60:40, 50/50, 40:60, 30:70 ...) AND/OR
- The duration of post-meal insulin delivery (3, 4, 6 hours,…)
Method B: Warsaw Method for Insulin Pump (simplified)
- Give pre-meal insulin for CHO based on usual ICR (normal bolus)
- Give post-meal bolus for protein + fat by:
Adding up all calories (kcal) from protein and fat ÷ 10 = the grams of CHO equivalent.
Deliver this insulin as square/extended wave over this suggested period of time:
- 10 g CHO equivalent delivered over 3 hr
- 20 g CHO equivalent delivered over 4 hr
- 30 g CHO equivalent delivered over 5 hr
- > 30g CHO equivalent delivered over 8 hr
- Example: Sue eats 45 grams of CHO and 300 kcal from protein and fat. Her ICR = 15. She gives:
Method C: New Zealand Method for Low Carbohydrate
For patients on diet of ≤100 g of carbohydrate per day.
- Calculate bolus for CHO using usual ICR ( e.g. 1 unit: for 10 g CHO)
- For protein dosing multiply ICRx2 (e.g. 1 unit: for 20 g PRO)
- No insulin is given for fat in this method
- This method is only appropriate for low carbohdyrate diets.
Example: Carlo eats 15 g CHO + 60 g protein. His ICR = 10.
- For carbohydrate he gives 15g/10 (ICR) = 1.5 units
- For protein he gives 60g/20 (ICR x 2) = 3 units
Method D: Insulin Pump Test Meals (with varied fat)
- 20 g fat: usual insulin for carb delivered as 75% normal bolus, 25% extended over 1.25 hr
- 40 g fat: usual insulin for carb delivered as 65% normal bolus, 35% extended over 1.25 hr
- 60 g fat: usual insulin +20% more insulin. Delivered as 50% normal bolus, 50% extended over 1.75 hr.
Per gram of nutrient:
- 1 g carbohydrate = 4 kcal
- 1 g protein = 4 kcal
- 1 g fat = 9 kcal
|Per Food Choice||kcal (calories)||g CHO||g PRO||g FAT|
|1 oz (30 g) lean meat/fish/poultry
1 oz (30 g) meat/fish/poultry
|1 tsp (5 mL) fat||45-50||0||0||5|
|1 grain choice-low fat (e.g. 1 bread)||70||15||3||0|
|1 cup (250 mL) milk||Skim 90
|Reference: Diabetes Canada, Beyond the Basics
Patient resources for nutrient searches: Product labels (the most accurate source) and Apps e.g. Fitness Pal and websites e.g. http://nutritiondata.self.com/ and https://www.calorieking.com/
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K.J.Bell, et. al. Impact of fat, protein, and glycemic index on postprandial glucose control in type 1 diabetes: Implications for intensive diabetes management in the continuous glucose monitoring era. Diabetes Care. 2015.38:1008-1015. https://doi.org/10.2337/dc15-0100
Pańkowska E, Szypowska A, Lipka M et al. Application of novel dual wave meal bolus and its impact on glycated hemoglobin A1C level in children with type 1 diabetes. Pediatric Diabetes 2009;10 (5):298-303 https://doi.org/10.1111/j.1399-5448.2008.00471.x
Jeremy D. Krebs, et al. The effect of additional mealtime insulin bolus using an insulin-to-protein ratio compared to usual carbohydrate counting on postprandial glucose in those with type 1 diabetes who usually follow a carbohydrate-restricted diet: A randomized cross-over trial. Diabetes Obesity & Metabolism.2018:1–4. https://doi.org/10.1111/dom.13392
Kirstine J. Bell,1 Chantelle Z. Fio,1 Stephen Twigg et al. Amount and Type of Dietary Fat, Postprandial Glycemia, and Insulin Requirements in Type 1 Diabetes: A Randomized Within-Subject Trial. Diabetes Care 2020;43:59–66 | https://doi.org/10.2337/dc19-0687