Читать книгу Diabetes Cookbook For Canadians For Dummies - Cynthia Payne - Страница 12

As many Canadians know – and proudly declare – insulin was discovered in Canada. (Want to learn more about the amazing story behind the discovery of insulin? We highly recommend reading the superb book The Discovery of Insulin, by Michael Bliss, University of Chicago Press.)

All people with type 1 diabetes require insulin therapy from the time of diagnosis. Many people with type 2 diabetes, given a sufficiently long time living with the condition, will also require insulin therapy because the pancreas in a person with type 2 diabetes gradually loses its ability to make insulin.

Insulin is given by a painless injection with a tiny needle into the abdominal wall, arms, legs, or buttocks. It is most easily administered using a pen device. Pens are small, convenient, portable, and available for free from pharmacies and diabetes education centres.

Looking at the types of insulin

A variety of different types of insulin therapy are available, each with its own specific properties. Combinations of different types of insulin are also available.

The various insulins can be grouped into three main categories:

✔ Rapid-acting and short-acting insulins are given before meals and prevent the carbohydrates you ingest from making your blood glucose levels rise excessively. The trade names for the available rapid-acting insulins are Apidra, Humalog, and NovoRapid.

✔ Intermediate and long-acting insulins are given to prevent your blood glucose level from rising too high between meals and, especially, overnight. The only intermediate-acting insulin used in Canada is called NPH. The trade names for the available long-acting insulins are Lantus and Levemir. Lantus and Levemir have a main advantage over NPH insulin in that they are far less likely to cause hypoglycemia.

✔ Premixed insulins are mixtures of both rapid-acting (or short-acting) insulin with intermediate-acting insulin and, as such, act to control both between-meal and after-meal blood glucose levels. Premixed insulins are typically given before breakfast and before dinner.

Using insulin and nutrition together: A recipe for success

Used individually, insulin and nutrition therapies are very helpful in keeping blood glucose levels in control. Used together they provide a simply awesome one-two punch.

The key element to achieving success with insulin therapy is to give the right amount of insulin to match your body’s needs. Your body’s needs will depend on many factors including, importantly, the types and amounts of food you eat, and the types and amounts of exercise you do.

Of the various types of foods you eat (and liquids you drink), the carbohydrates influence your blood glucose levels and insulin requirements the most. In general, the more carbohydrates you ingest, the more your blood glucose level will potentially go up and thus the more insulin you need to take to prevent this from happening. (The main exception to this is if you’re eating carbohydrates in the form of fibre; fibre does not make blood glucose levels go up.)

If everything else in your life is stable (exercise, stress, general health, and so forth), and if you ingest a very similar amount of carbohydrate day-to-day, then you will likely find the amount of insulin you need to take to keep your blood glucose levels in check will be quite consistent. If, however, the amount of carbohydrate you eat (both in terms of types and quantities) varies quite a bit, then you will need to regularly adjust your insulin dose to match your intake. The best way to do this is to use a technique called carbohydrate counting. We look at this topic next.

Carbohydrate counting

Carbohydrate counting involves calculating how many grams of carbohydrate (“carbs”) – excluding fibre – you are about to eat and giving an amount of rapid-acting insulin proportionate to this. For most people, the formula works out to about one unit of insulin for every 10 grams of carbohydrate. For example, if you are about to eat a meal that contains 50 grams of carbohydrate (again, fibre isn’t included in the calculation), you would need to give yourself five units of insulin.

The other key factor in determining how much rapid-acting insulin you require before a meal is your blood glucose level before the meal. If your blood glucose level is high before your meal, you’ll need to take extra insulin to bring it down. This extra insulin is called a correction factor or sensitivity factor and is usually about one unit of insulin for every 3mmol/L your blood glucose level is above 7 or so.

Carbohydrate counting isn’t rocket science, but it isn’t easy either. To master carbohydrate counting requires quite a bit of guidance from a skilled dietitian. And even when you’ve learned the ropes, periodic visits to the dietitian to reinforce the skills you’ve learned are a good idea.

In the accompanying sidebar (“Using carb counting and a correction factor”), we give an example of how to effectively use carbohydrate counting and a correction factor.

Using carb counting and a correction factor

Here’s an example of how to use carb counting and a correction factor.

Let’s say you’re about to eat a dinner that has 70 grams of carbohydrate (including 10 grams of fibre) and your before-meal blood glucose level is 13mmol/L. You are, say, using a carbohydrate counting ratio of 1 unit of insulin per 10 grams of carbohydrate and a correction factor of 1 unit of insulin per 3mmol/L your blood glucose level is above 7.

You will be eating 70 grams of carbohydrate but you exclude the 10 grams of fibre you’ll be eating from your calculations because the fibre doesn’t raise blood glucose. (The amount of fibre in a product is listed on the Nutrition Facts table.) Therefore, 70 grams of carbohydrate minus 10 grams of fibre leaves you with 60 grams of carbohydrate to use for your remaining calculations.

Because you’re now dealing with 60 grams of carbohydrate and you take one unit of insulin per 10 grams, that would mean you need six units of insulin to “cover” the food you’re about to eat.

Because your blood glucose is 13mmol/L and you need to take an extra one unit for each 3mmol/L above 7, you need to take an extra two units of insulin to “correct” the elevated blood glucose level.

You add the six units (from your carb counting) and the two units (from your correction factor), and thus you’d take a total of eight units of insulin.

Even if you aren’t taking insulin, being familiar with the number of grams of carbohydrates in the foods you eat is helpful. This will help you stay on track with making sure you get the proper quantities of carbohydrates in your diet and that you maintain balance between the amount of carbohydrates, proteins, and fats you consume.

Fibre is a carbohydrate that doesn’t influence blood glucose. In the recipes in this book, we note the available carbohydrate, which is the total carbohydrate minus the fibre. This is the carbohydrate amount you need to keep track of.