Insulin management in patients with Type 1 Diabetes (S1/05)

It is important to be careful about what you eat, even if you don’t have diabetes. It will be much more rewarding if you are able to discuss what you can eat with a dietitian who will help you draw up a meal plan based on the mealtimes, routines and preferences that are important to your family. “You should never eat what you don’t like”, says UK dietitian Sherry Waldron.

This study will give you many details about blood glucose and different foods, but you will learn the general aspects of healthy eating from your dietitian.

Based of ADA (America Diabetes Association) and ISPAD (International Society for Pediatric and Adolescent Diabetes) guidelines, Postprandial glucose level is recommended to be less than 180 mg/dl (10 mmol/L)

Current Standard of Care:

Dosing insulin solely based on carbohydrate (CHO) content of meal. (Blood glucose in range might become more feasible)

Glycaemic Effects of Dietary Fat

Fat delays gastric empting, increases insulin resistance (the inability of cells to adequately use circulating insulin, resulting in increased levels of blood glucose.)
Fat also increases gluconeogenesis (the process by which the liver produces glucose from fat and proteins to raise the blood glucose level) 
There are several mechanisms, including increasing GLP1 (glucagon-like peptide) and GIP (Gastric inhibitory polypeptide); suppression of Ghrelin (hunger hormone) 
Free fatty acids limit glucose uptake into peripheral tissues

Effects of GLP-1:

1. stimulates the production and release of insulin,
2. decreases the production of glucagon,
3. slows down the emptying of the stomach and
4. decreases appetite.

Glycaemic Effects of Dietary Protein 

Protein increases cortisol (hormone produced in response to stress & affects the body metabolism), growth hormone, 1GF-1 (Insulin-like growth factor 1), and ghrelin
It also increases gluconeogenesis 

Effects of Cortisol:

1. Cortisol raises blood glucose by:
Reducing cellular uptake of glucose.
Breaking down proteins that can be used to produce glucose in the liver. 
2. It also stimulates breakdown of body fat into fatty acids that can be converted into ketones.

Effects of growth hormone:

1. It stimulates growth.
2. It raises blood glucose by reducing the cellular uptake of glucose.
3. It breaks down body fat.
4. It increases muscular mass

Therefore, dietary fat and protein should be considered in meal bolusing.

“A conservative starting point for incremental bolus dose increases is an additional 15% to 20% for high fat, high-protein meals.”

The emptying of the stomach is also affected by the blood glucose level. The stomach empties more quickly if the blood glucose is low and more slowly if it is high. Both solid and liquid food are emptied from the stomach twice as fast when the blood glucose drops from a normal level 4-7 mmol/l (70-125 mg/dl) to a hypoglycaemic level (1.6-2.2 mmol/l, 29-40 mg/dl), as was postulated by (Dr Ragnar Hanas, 2019).

Dietary Fat Acutely Increases Glucose Concentrations and Insulin Requirements in Patients with Type 1 Diabetes

On the implications for carbohydrate-based bolus dose calculation and intensive diabetes management: High Fate (HF) required more insulin (about 42% extra) than Low Fat dinner and caused more hyperglycaemia (5-10 hrs) following High fat meals.

Both Dietary Protein and Fat Increase Postprandial Glucose Excursions in Children with Type 1 Diabetes and the Effect is Additive:

Meals high in protein or fat increase glucose excursions from 3hrs to 5hrs following meals
Protein and fat have an additive impact on the delayed postprandial glycaemic rise.
Protein has a protective effect on the development of hypoglycaemia 

Influence of Dietary Protein on postprandial blood glucose levels in individuals with Type 1 diabetes mellitus using intensive insulin therapy:

“Seventy-five grams (75g) or more of protein alone significantly increases postprandial glycaemia from 3hrs to 5hrs”, (Diabetes UK, 2015).

Summary 1: Postprandial Glucose Excursion 

High fat meal reduces the initial postprandial glycaemic rise.
High fat dinner requires more insulin and causes more hyperglycaemia.
Protein and fat have an additive impact on delayed postprandial hyperglycaemia.
Seventy-five grams (75g) or more of protein alone significantly increases postprandial glycaemia from 3hrs to 5hrs.

Dietary protein affects both the dose and the pattern of insulin delivery required to achieve postprandial euglycaemia ( a normal blood glucose in the blood) in Type 1 diabetes 

A high-protein (60 grams) meal requires ~50% more insulin.
Inter-individual differences exist in insulin requirements for dietary protein.

Summary 2: Insulin Requirements

Following the addition of 40g of fat and 27g of protein to 50g of Carbohydrate: increase in insulin by 65% ± 10%: 30%/70% split over 2.4hrs
60 gram of protein required ~50% more insulin: the majority within the first 2hrs.
High-fat and high-protein meals require a ≥60% insulin: Carbohydrate ratio as a standard bolus to control the initial postprandial rise. Additional insulin up to 70% in needed to the extended bolus.

Does Type of Fat Matter?

Extra-virgin olive oil (high-monounsaturated fat) may lower glycaemia by:
Changes in gastric emptying
GLP-1 secretion
Reducing glucose absorption

Amount and Type of Dietary Fat, Postprandial Glycaemia, and Insulin Requirements in Type 1 Diabetes:

The type of fat had no impact on postprandial glycaemia.
The amount of fat has a significant, dose-dependent effect.

For Patients on multiple daily Injections (MDI) 

Rapid-acting and Regular Insulin are equal for High Fat-Protein Meal in Individuals with Type 1 Diabetes Treated with Multiple Daily Injections (Karolina J, Piotr M, Krzystof Safranow & Diabetes Therapy, 2018). 

NB. No benefit to cover fat-protein meals with regular insulin in individuals with Type 1 Diabetes treated on MDI


According to Dr. Ragnar Hanas, the reason that individuals with diabetes should be careful with fat intake is that they have an increased risk of arteriosclerosis and heart disease. A key goal for people with diabetes is to decrease the intake of total fat (including saturated fat and trans fatty acids) and cholesterol. Foods that contain large amounts of saturated fats include dairy products and red meats. 

Try to use monounsaturated and polyunsaturated fats where possible instead. Ordinary margarine and butter contain only 3% polyunsaturated fat. An increased intake of monounsaturated fats may even improve your HbA1c

Factors that increase the blood glucose level more slowly (decreased glycaemic index)

Factors that increase the blood glucose level more quickly (increased glycaemic index)

1.       Starch structure: Boiled and mashed potatoes give a quicker blood glucose response (as fast as ordinary sugar) while rice and pasta give a slower blood glucose response

2.        Gel-forming dietary fibre: A high fibre content (as in rye bread) gives a slower rise in blood glucose by slowing down the emptying rate of the stomach and binding glucose in the intestine.

3.       Fat content: Fat in the food will delay the emptying of the stomach.

4.       Cell structure: Beans, peas and lentils retain their cell structure even after cooking. Whole fruits affect the blood glucose level more slowly than peeled fruits and juice

5.       Size of bites: Larger pieces of food take longer to digest in the stomach and intestine. Larger pieces also cause the stomach to empty more slowly.

1.       Cooking: Boiling and other types of cooking will break down the starch in food.

2.       Preparing food: Prepared food, e.g. polished rice will give a quicker rise in blood glucose than unpolished, mashed potatoes quicker than whole potatoes and grated carrots quicker than sliced. Wheat flour gives a higher blood glucose response when baked in bread than when used for pasta.

3.       Fluids with food: Drinking fluids with a meal causes the stomach to empty more quickly.

4.       Glucose content: Extra sugar as part of a meal can cause the blood glucose level to rise, but not by as much as was once believed. Particle size and cell structure in different food compounds give them different blood glucose responses in spite of their containing the same amount of carbohydrates.

5.       Salt content: Salt in the food increases the absorption of glucose into the bloodstream.

Food rules of thumb

Regular eating habits are encouraged in all children and adolescents, with or without diabetes.
Plan mealtimes and contents with other daily activities in mind, e.g. will you be taking physical exercise or sitting at a desk?
Always take a dose of insulin when eating something extra, e.g. at parties, or when eating sweet things.
Eat fresh fruit as a snack rather than drinking fruit juice.
Cut down on snacks and what you eat at every meal if you have weight problems.
Aim for a high fibre content in your food.

Practical Tips

For high fat meal > 3grams: Consider increasing insulin dose by 30%
If on Insulin pump: Use an extended bolus 60% upfront and 40% over 2-4 hrs
If on injection: 60-65% upfront and 35% one hour after meal

In conclusion, the fat in food must pass into the intestine before it can affect the emptying rate of the stomach. This means that if you start a meal with something rich in fat, the signal that slows down the emptying rate will reach the stomach more quickly. If you eat a meal very rich in fat, you may still have food remaining in your stomach when you are about to have your next meal. If you are using multiple injections, you will need to decrease the amount of food you plan to eat (without changing the insulin dose), if you are to avoid an increase in blood glucose, as was propagated by (Dr Ragnar Hanas, MD)

Acknowledgements to @Laya Ekhlaspour, MD @Dr Ragnar Hanas, MD, Ass. Prof.


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