Nutrition and Carb Counting
Carb counting helps people with type 1 diabetes match insulin to food by estimating how many carbohydrates are in a meal. It supports better blood sugar control, reduces highs and lows, and improves overall diabetes management.
This content is not medical advice. Always consult your healthcare or diabetes care team before making any changes to your diabetes treatment or daily management.
Nutrition Fundamentals
Your meals combine three main macronutrients: carbohydrates, protein, and fats plus hydration from water and water rich foods. Carbs drive blood sugar changes, protein and fats help smooth those effects and good hydration supports insulin action and digestion. Learning what each does and how to pair them makes blood sugar more predictable and helps prevent big swings.
Carbohydrates
What they are? Carbohydrates are a primary energy source in food, but they have the most direct effect on blood sugar because they break down into glucose.
Types:
Fast carbs – digest quickly and cause a rapid rise in blood sugar. Examples: white bread, white rice, juices, candies, soda.
Slow carbs – release energy more gradually, so blood sugar rises more gently. Examples: oats, whole grains, beans, lentils, most vegetables (especially non-starchy), berries.
Why they matter?
The amount and type of carbohydrate you eat determine how much your blood sugar will rise after a meal. Learning to count or estimate grams of carbs and pairing them with other macronutrients is key to avoiding sharp spikes and drops.
Common Carbohydrate Foods
All types of bread, oats, rice, pasta, potato, sweet corn, beans, peas, lentils, chickpeas, and broad beans.
All kinds of fruit, including dried fruit.
Milk and some dairy products.
Glucose and sugar in all forms, and sugar-sweetened beverages.
Jam and honey.
Cakes, chocolate, candies, and ice cream.
Protein
What it is? Protein is the body’s building block — it helps maintain muscle, keeps you feeling full, and by itself does not raise blood sugar quickly like carbs do.
Sources:
Animal-based: chicken, turkey, fish, eggs, low-fat cheese.
Plant-based: lentils, tofu, tempeh, nuts, seeds, quinoa.
Why it matters?
Adding protein to a meal with carbohydrates slows digestion and helps blunt sudden blood sugar rises. It also helps you feel satisfied longer, reducing unnecessary snacking.
Foods High in Protein
Lean ham, cold cuts, and sausages with less than 20% fat
Lean (tough) meats: veal, beef, poultry, turkey, rabbit
Lean fish and shellfish: e.g., crustaceans, trout, shrimp, cod
Low-fat cheese (20% fat or less)
Cottage cheese
Soy products
Egg white
If you eat these foods, your blood glucose value will not rise. You can eat these foods in amounts similar to people who do not have diabetes.
Fats
What they are? Fats are a concentrated energy source; they help absorb fat-soluble vitamins (A, D, E, K) and do not directly raise blood sugar. However, different fats affect health differently.
Types:
Healthy (unsaturated): olive oil, avocado, nuts, seeds, fatty fish (salmon, mackerel).
Saturated / less ideal in excess: fatty red meat, full-fat dairy, fried foods.
Trans fats: industrially hydrogenated fats (should be avoided).
Why it matters?
Fats slow gastric emptying, so when combined with carbohydrates, they can soften the blood sugar rise. They also help with satiety and sustained energy.
High-Fat Foods
Butter, margarine, oil
Fatty meat and sausages (over 20% fat)
Fatty fish (e.g., eel, mackerel)
Cheese with over 20% fat
Walnuts
Avocado
Egg yolk
Water-rich Foods (Hydration through Food)
Why they matter?
Water is essential for circulation, kidney function, digestion, and even blood sugar regulation. Good hydration helps the body use insulin effectively and clear waste. Foods high in water contribute to hydration, add volume to meals (helping with satiety) without many calories, and can slow eating.
Additional benefits:
Water-rich foods increase the volume of a meal without adding excessive carbs or fats, helping you feel full sooner.
Pairing meals with these (e.g., a salad before the main course, soup or water with a meal) can reduce overall intake.
Foods that contain mostly water
eggplant, cauliflower, green beans, broccoli, chicory, cucumber, leafy lettuce, fennel, cabbage, carrot, kohlrabi, leek, Swiss chard, bell pepper, fresh mushrooms, radicchio, radish, celery, Brussels sprouts, beetroot, rhubarb, sauerkraut, asparagus, spinach, vegetables, tomatoes, onion, zucchini.
You can eat these foods in unlimited amounts.
Large amounts of fat (especially unhealthy saturated or trans fats) over time can affect insulin sensitivity, which may make blood sugar control more difficult for some people.
Glycemic Index and How Food Affects Blood Glucose?
The glycemic index (GI) is a tool used to indicate how much certain foods raise blood glucose (BG) levels. It compares the rise in BG caused by a specific food to the rise caused by pure glucose or white bread, both of which are assigned a GI value of 100.
The effect of pure glucose on BG = 100 (measured over three hours).
While GI provides a helpful estimate, it’s important to understand that many factors influence how food affects blood sugar including how the food is prepared and what it’s eaten with.
Examples of GI Ranges and Foods:
GI 90–100% (High Impact on BG):
Maltose (malt sugar), instant mashed potatoes, baked potatoes, honey, white rice, quick-cooking rice, steamed rice, cornflakes, glucose, cola.
GI 50–90% (Moderate to High Impact):
White bread, rye bread, crispbread, oatmeal, pudding mixes, wheat flour, cookies, beer, oat-based pastries, bananas, table sugar, dark rye bread, whole grain bread, unsweetened fruit juices.
GI 30–50% (Low to Moderate Impact):
Milk, yogurt, fruit, pasta, ice cream.
Other Factors That Influence Blood Sugar:
The rise in BG doesn’t depend solely on GI. Several other things can affect how your body responds:
More fiber or fat slows digestion, leading to a smaller and slower BG rise.
Preparation method matters: For example, apple juice raises blood sugar faster than a whole apple. Mashed potatoes raise BG faster than boiled ones.
Liquids are absorbed faster than solids, which often leads to quicker spikes.
Foods with Little Impact on Blood Glucose
Carb counting is a way for people with type 1 diabetes to dose insulin based on how many grams of carbohydrates are in a meal, instead of giving insulin “blindly”. Carbohydrates found in bread, rice, fruit, dairy, sugary drinks, and many other foods break down into glucose and raise blood sugar. By estimating the grams of digestible carbohydrates in a meal and applying a personal insulin-to-carb ratio (for example, 1 unit of insulin for every 10 grams of carbs), insulin can be matched to the expected glucose rise.
Foods That Have a Mild Impact on BG After Meals
Legumes (beans, peas, lentils, broad beans, chickpeas) contain more carbohydrates than most vegetables, but their impact on BG is lower because they are rich in fiber and digest slowly.
Still, the amount of carbs should be counted, especially in larger portions.
Foods Where Carb Counting Is Necessary
You should count carbohydrates in foods that contain starch, such as grains and grain-based products, and starchy vegetables like potatoes.
Starch breaks down fully into glucose, so its impact on BG is significant.
Other carbohydrates like maltose and lactose are only partially broken down into glucose. Fruits, on the other hand, contain a lot of fructose, which raises BG more slowly than glucose, but should still be accounted for in total carb intake.
Carbohydrate Counting
To eat a varied and balanced diet, it’s important to know how to calculate the amount of carbohydrates in different foods. A standard reference unit of 15 g of carbohydrates (excluding fiber) is commonly used to help with counting and meal planning.
For example, half of a bread roll or half a slice of rye bread contains about 15 g of carbohydrates. All foods can be compared based on this reference amount. For instance, a small pear and half a banana have roughly the same amount of carbohydrates and can be considered interchangeable.
Insulin dosing:
For every 15 g of carbohydrates, 1 unit (IU) of rapid-acting insulin may be needed (e.g., if you want to eat two apples, you might need 2 units of rapid-acting insulin).
However, individual needs vary, so you should always consult your endocrinologist or diabetes educator to determine your exact insulin-to-carb ratio.
Grams of carbohydrates / Insulin-to-Carb ratio (I:C) = Number of rapid-acting insulin units
Example:
If you eat a meal that contains 60 grams of carbohydrates, and your personal ratio is 1:15 (1 unit of insulin for every 15 grams of carbs):
60 ÷ 15 = 4 units of insulin
The insulin-to-carb ratio (I:C) determines how much rapid-acting insulin is needed for a specific amount of carbohydrates consumed.
For most adults, a common starting ratio is 1 unit of insulin per 15 grams of carbs (1:15).
For children, the ratio is often more sensitive, typically around 1 unit per 10 grams of carbs (1:10).
However, this ratio can vary significantly from person to person and may change over time, depending on age, physical activity, time of day, and overall insulin sensitivity.
Wondering how many carbs are in a banana, a slice of bread, or a handful of grapes? Download our printable carb count charts by food group and make carb counting simpler — whether you’re just starting out or need a quick daily reference.
Join as a T1D Warrior
Our T1D Warriors are children, parents of children with diabetes, and individuals living with type 1 diabetes who share their personal experiences to inspire and support others. Every story, every blog post, and every piece of advice you find here comes from someone who has truly lived it — with honesty, courage and a whole lot of heart. Together, we’re building a community where real-life experience truly makes a difference.
Want to inspire others with your T1D journey? Become a T1D Warrior and share your story.