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Type 1 Diabetes

By Sarah Carney, Nutritionist (BSc)

What is Type 1 Diabetes?

Type 1 Diabetes (T1D) is an autoimmune condition where the pancreas cells (Beta-cells) no longer produces the hormone' insulin.' Insulin is a peptide hormone needed by the body to metabolise the body's primary energy source of carbohydrates.

What is the cause of Type 1 Diabetes?

The exact cause of T1D is currently unknown. However, different factors such as genetics and possibly exposure to certain viruses and other environmental factors may contribute to T1D.

Who does Type 1 diabetes affect, and what is the prevalence?

T1D mainly affects young children and teenagers. However, it can develop in adulthood too! In Ireland, Type 1 Diabetes accounts for almost 20,000 of the total diabetes population (i.e., 10-15% of the people living with diabetes)(1).

Symptoms of Type 1 Diabetes?

Think of the 4 T's!

  • Toilet (are you going to the toilet more frequently?)

  • Thinness (have you lost weight?)

  • Thirsty (having trouble to quench your thirst?)

  • Tired (tired than usual?)

Management/ treatment of Type 1 Diabetes?

Despite the efforts of ongoing research, there is no cure for T1D. People with Type 1 diabetes have to manage their diabetes by controlling blood glucose levels with insulin, diet, insulin, and lifestyle adjustments to prevent complications.

Optimal Blood Sugar Levels

In T1D, ideally, you want your blood sugar levels to be between 4-8mmol/L.

Before meals, blood sugar levels should be between 4-7mmol/L and 9mmol/L 2 hours after meals. Every 3-6 months, a person with T1D should have their HbA1c measured. HbA1c is your average blood glucose (sugar) levels for the last two to three months. If you have diabetes, an ideal HbA1c level is 48mmol/L (6.5%) or below.


Insulin is a peptide hormone needed by the body to allow glucose into the body's energy cells. However, since people with T1D cannot produce insulin, they need to take multiple daily injections (MDI). There are many different types of insulin, such as basal and bolus insulins.

  1. Basal insulins (e.g., Levemir/Lantus): This type of insulin maintains blood sugar levels over a 24-hr period and needs to be injected either once or twice a day, depending on the type of insulin.

  2. Bolus insulins (e.g., Novarapid/Fiasp): This type of insulin is taken with meals that contain carbohydrates. This insulin works quickly and tries to reduce blood sugar spikes after a meal is ingested. The number of these injections will depend on the individual. A person with T1D works closely with a Registered Dietitian to adjust the dose of this insulin.

Carbohydrate Counting

Carbohydrate counting or carb counting is a meal planning strategy that matches the amount of carbohydrate ingested to available insulin to allow optimal glycaemic control with dietary flexibility. Carbohydrates can be counted in two different ways, in grams or as carbohydrate portions (CPs). Usually, one CP is equal to 10g of carbohydrates. Once someone with diabetes gets the hand of estimating the carbs in food and drink, one will need to know their insulin-to-carb-ratios (ICR).

Insulin to Carb Ratios

Insulin to Carb Ratios (ICRs) varies from person to person. It can depend on an individual's age, weight, activity levels, and insulin sensitivity. A dietitian works alongside the individual with T1D to help work out the ICRs for each meal. Usually, a dietitian will start a person with T1D at an ICR of 1:1 and closely monitor blood sugar levels.

If one knows how many carbohydrates are in a meal and your ICR, you can work out the number of bolus insulin units to give. For example, if a meal had 70g of carbohydrates and your ICR was 1 unit of insulin for every 10g carbohydrate, one would need to take 7 units of bolus insulin (2).

Hypoglycemia (Low blood sugar)

Hypoglycemia is also known as low blood sugar (<4mmol/L). This can occur when too much insulin is given or unplanned activity. Low blood sugar symptoms include:

  • Sweating

  • Rapid heartbeat

  • Dizziness/confusion

  • Blurred vision

When someone has low blood sugar (hypo), they should take 10-20g of rapid-acting carbohydrates such as 3-4 dextrose tablets or fruit juice (100ml).

Hyperglycaemia (High blood sugar)

Hyperglycaemia is also known as high blood sugar (<10mmol/L). This can occur when someone with diabetes has miscalculated their meal's carbohydrate content or if they forget to administer insulin. Symptoms of high blood sugar include:

  • Frequent urination

  • Increased thirst

  • Headaches

When someone has high blood sugar, they should take a correction dose of insulin or do some gentle exercise such as a walk to help lower blood sugar levels.

Alcohol & Type 1 Diabetes (3)

If you have T1D, you can still drink alcohol. However, you need to take care of the amount and the type of alcohol you drink, as alcohol can increase the risk of hypos. Here are some tips to remember when drinking with T1D:

  • Be prepared- carry hypo treatments with you like dextrose tablets and test your blood sugar levels regularly.

  • Tell your friends you have diabetes and what to do if you have a hypo.

  • Don't drink on an empty stomach- eating foods that contain carbohydrates before a night out can help avoid a hypo.

  • Have a snack before you go to sleep- test blood sugar levels before you sleep to prevent a hypo at night while sleeping.

Exercise & Type 1 Diabetes

Exercise is encouraged with T1D as it can help manage blood sugar levels, improve cardiovascular fitness, better bone health, and increased psychological well-being (4). Young adults with T1D should be aiming for 150 minutes of moderate activity (e.g., walking/cycling) per week (5). People with T1D need to balance insulin dosing and food intake to maintain blood sugar levels in a normal range before, during, and after exercise. It is also a good idea to carry hypo treatments with you when you exercise to avoid a hypo when exercising.

Technological advances in Type 1 Diabetes?

A variety of technological advances have significantly improved the lives of people living with T1D. Advances include insulin pumps, continuous glucose monitors, and systems that combine both a pump and a monitor for algorithm-driven administration of insulin delivery (6).

About The Author

Sarah Carney, Nutritionist (BSc)

MSc Student Dietician

Instagram: @didyouknowimdiabetic

Sarah Carney is a Registered Associate Nutritionist. She recently graduated from UCD with a degree in Human Nutrition. She is currently an MSc. Student Dietitian at Ulster University. After being diagnosed with Type 1 Diabetes when she was 15, she wanted to pursue a nutrition and dietetics career to learn more about how nutrition affects T1D, and to help other people with the management of their diabetes.




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