Friday, November 08, 2013

ADA Position Statement On Nutrition Therapy For Diabetes: Carbohydrate

The American Diabetes Association (ADA) recently published their new Position Statement on nutrition therapy for people with diabetes:

Nutrition Therapy Recommendations for the Management of Adults With Diabetes, Diabetes Care, Published online ahead of print, 9 October 2013.

This post focuses on carbohydrate, specifically amount. Subsequent posts will address fat, protein, and other dietary considerations.

The Statement used a grading system to rate the evidence, evidence which formed the basis for their recommendations. A description of that grading system can be found in Table 1 of their Statement on medical care:

ADA Position Statement, Standards of Medical Care in Diabetes - 2013, Diabetes Care, January 2013

For convenience, I'm including it here:

Table 1. ADA Evidence Grading System For Clinical Practice Recommendations (Grade, followed by description):

  • Clear evidence from well-conducted, generalizable RCTs that are adequately powered, including:
    • Evidence from a well-conducted multicenter trial
    • Evidence from a meta-analysis that incorporated quality ratings in the analysis
  • Compelling nonexperimental evidence, i.e., “all or none” rule developed by the Centre for Evidence-Based Medicine at the University of Oxford
  • Supportive evidence from well-conducted RCTs that are adequately powered, including:
    • Evidence from a well-conducted trial at one or more institutions
    • Evidence from a meta-analysis that incorporated quality ratings in the analysis
  • Supportive evidence from well-conducted cohort studies
    • Evidence from a well-conducted prospective cohort study or registry
    • Evidence from a well-conducted meta-analysis of cohort studies
  • Supportive evidence from a well-conducted case-control study
  • Supportive evidence from poorly controlled or uncontrolled studies
    • Evidence from randomized clinical trials with one or more major or three or more minor methodological flaws that could invalidate the results
    • Evidence from observational studies with high potential for bias (such as case series with comparison with historical controls)
    • Evidence from case series or case reports
  • Conflicting evidence with the weight of evidence supporting the recommendation
  • Expert consensus or clinical experience

Regarding carbohydrates, the panel gave these recommendations:
The amount of carbohydrates and available insulin may be the most important factor influencing glycemic response after eating and should be considered when developing the eating plan. Grade A

Monitoring carbohydrate intake, whether by carbohydrate counting or experience-based estimation remains a key strategy in achieving glycemic control. Grade B

For good health, carbohydrate intake from vegetables, fruits, whole grains, legumes, and dairy products should be advised over intake from other carbohydrate sources, especially those that contain added fats, sugars, or sodium. Grade B

Evidence is inconclusive for an ideal amount of carbohydrate intake for people with diabetes. Therefore, collaborative goals should be developed with the individual with diabetes. Grade: C
Note that although the amount of carbohydrate may be the most important factor influencing blood glucose, the panel felt that evidence was insufficient to state a specific amount for all people with diabetes. Although some studies that investigated low-carb eating patterns showed better serum lipids and blood glucose control, many were small, of short duration, and/or had low retention rates which could bias results. As well, some studies showed no significant difference in lipid and glucose markers between low-carb and higher-carb diets.
Evidence suggests that there is not an ideal percentage of calories from carbohydrate, protein, and fat for all people with diabetes. Grade B

Macronutrient distribution should be based on individualized assessment of current eating patterns, preferences, and metabolic goals. Grade E
The panel revealed that, on average, people with diabetes eat about 45% of their calories from carbohydrate, 36-40% from fat, and 16-18% from protein. However, diets with more or less carbohydrate, fat, and protein have been shown to be effective in managing diabetes. Those diets included the Mediterranean, DASH (Dietary Approaches to Stop Hypertension), plant-based (vegan and vegetarian), low-fat, and low-carbohydrate.

Reciting a chorus of this Statement, the panel stressed that individualization was key in determining an optimal mix of macronutrients. Health status (e.g. renal function and body weight) as well as food preferences should be considered.