Building Competency in Diabetes Education THE ESSENTIALS

TREATMENT MODALITIES: LIFESTYLE| 5-11

CARBOHYDRATES

Carbohydrates provide 45 to 60% of daily energy intake.

Dietary carbohydrates come from cereals, breads, rice, pasta, other grain products, legumes, some vegetables, fruits, some dairy products and added sugars. Approximately 90 to 100% of ingested carbohydrate will be absorbed as glucose in the bloodstream (25). Both the source and the amount of carbohydrate consumed influence postprandial glycemic response. The terms “simple” and “complex” are no longer used to classify carbohydrates, as they do not help to determine the impact of carbohydrate on BG levels (5). There is little scientific evidence to support the assumption that simple sugars are more rapidly digested and absorbed than complex carbohydrates. Although the source or type of carbohydrate in foods does influence postprandial glucose levels, the total amount of carbohydrate consumed is usually more important (26). The recommended dietary allowance for digestible carbohydrate is not less than 130 g per day (27). This value is based on the average minimum amount of glucose that is used by the brain. It is intended to prevent the rise in ketoacid production that would occur when insufficient glucose is available (27). Systematic reviews and meta-analyses of controlled trials of carbohydrate-restricted diets (mean carbohydrate of 4% to 45% of total energy per day) for people with type 2 diabetes have not shown consistent improvements in metabolic parameters. Overall, low-carbohydrate diets failed to show superiority over higher carbohydrate intakes for weight loss, glycemic control, lipid concentrations, blood pressure, and adherence with treatment (28,29,30). Very-low-carbohydrate diets have ketogenic effects that may increase risk of diabetic ketoacidosis for those taking insulin or SGLT2 inhibitors (31) (see Chapter 6: Treatment Modalities: Pharmacological Therapies). A limited number of small, short-term studies conducted on people with type 1 diabetes using a low-carbohydrate diet (target <75g/day) have demonstrated improved A1C for those who are able to adhere to the diet (32,33). However, there is a concern that there may be a blunted response to a glucagon bolus which would have an impact on the treatment of hypoglycemia (34). The long-term sustainability of these diets remains uncertain. As well, these types of diets eliminate many foods that are important sources of energy, fibre, vitamins and minerals and are important in dietary palatability (21). In general, at least 100 g of carbohydrate per day is recommended to spare protein breakdown and limit muscle wasting, and to avoid large shifts in fluid balance and ketosis (27).