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Recommendations Summary

PDM: Glycemic Index/Glycemic Load and Prevention of Type 2 Diabetes 2014

Click here to see the explanation of recommendation ratings (Strong, Fair, Weak, Consensus, Insufficient Evidence) and labels (Imperative or Conditional). To see more detail on the evidence from which the following recommendations were drawn, use the hyperlinks in the Supporting Evidence Section below.


  • Recommendation(s)

    PDM: Glycemic Index/Glycemic Load and Prevention of Type 2 Diabetes

    If the use of glycemic index/glycemic load is proposed for the prevention of type 2 diabetes, the registered dietitian nutritionist (RDN) should advise individuals who are at high risk for type 2 diabetes that a reduction in glycemic index/glycemic load alone, without weight loss, may or may not be beneficial. Limited research in both adults with metabolic syndrome and individuals with prediabetes reported that a reduction in glycemic index/load results in improvements in postprandial blood glucose values, independent of weight loss.

    Rating: Weak
    Conditional

    • Risks/Harms of Implementing This Recommendation

      The RDN should be aware that the relationship between consumption of low-glycemic index foods and plasma glucose concentration is complex and is altered by the protein and fat composition of a meal, preparation and processing of the food items, prior food intake, fasting or preprandial plasma glucose levels and degree of insulin resistance.

    • Conditions of Application

      • This recommendation applies when the use of glycemic index/glycemic load is proposed for the prevention of type 2 diabetes
      • Research on synergistic effects of nutrients was not evaluated.

    • Potential Costs Associated with Application

      The costs of medical nutrition therapy (MNT).

    • Recommendation Narrative

      A total of four studies were included in the evidence analysis for this recommendation:

      • One neutral-quality randomized controlled trials (RCT) (Wolever and Mehling, 2003)
      • Three neutral-quality randomized crossover feeding trials (Perala et al, 2011; Konig, Muser et al, 2012; Konig, Theis et al, 2012).

      In Adults with Metabolic Syndrome

      • Glycemic-related outcomes (FBG, random BG, two-hour post-prandial BG, A1C)
        • Two feeding studies regarding the impact of glycemic index/load reported a significant decrease in post-prandial glycemic outcomes in adults with metabolic syndrome
        • Intervention studies are needed to ascertain an effect of glycemic index/load on glycemic-related outcomes in adults with metabolic syndrome with or without meeting the metabolic syndrome criteria for impaired glucose tolerance and impaired fasting glucose
        • Evidence is based on the following: Konig, Muser et al, 2012; Konig, Theis et al 2012.
      • Lipid outcomes (TG, HDL):
        • One feeding study reports no significant effect of glycemic index/load on triglyceride or HDL-cholesterol levels in adults with metabolic syndrome
        • Intervention studies are needed to ascertain an effect of glycemic index/load on lipid outcomes in adults with metabolic syndrome with or without meeting the metabolic syndrome criteria for lipid levels
        • Evidence is based on the following: Konig, Theis et al, 2012.
      • Anthropometric outcomes (WC, WHR):
        • There were no studies identified to evaluate the impact of glycemic index/load on anthropometric outcomes in adults with metabolic syndrome
        • Intervention studies are needed to ascertain an effect of glycemic index/load on anthropometric outcomes in adults with metabolic syndrome with or without meeting the metabolic syndrome criteria for anthropometric measures.
      • Blood pressure outcomes:
        • There were no studies identified to evaluate the impact of glycemic index/load on blood pressure in adults with metabolic syndrome
        • Intervention studies are needed to ascertain an effect of glycemic index/load on blood pressure in adults with metabolic syndrome with or without meeting the metabolic syndrome criteria for blood pressure.
      • Renal outcomes:
        • There were no studies identified to evaluate the impact of glycemic index/load on renal outcomes in adults with metabolic syndrome
        • Intervention studies are needed to ascertain an effect of glycemic index/load on renal outcomes in adults wtih metabolic syndrome with or without meeting the metabolic syndrome criteria for renal measures.

      In Individuals with Prediabetes

      • Glycemic-related outcomes (FBG, random BG, two-hour post-prandial BG, A1C)
        • One intervention study and one feeding study regarding the relative reduction of glycemic index/load reported a significant decrease in post-prandial glycemic outcomes in individuals with prediabetes
        • Additional longer-term intervention studies are needed to ascertain the effects of relative reduction as well as low glycemic index/load values on glycemic outcomes in individuals with prediabetes
        • Evidence is based on the following: Wolever and Mehling, 2003; Perala et al, 2011.
      • Lipid outcomes (TG, HDL):
        • One intervention study and one feeding study regarding the relative reduction of glycemic index/load reported inconclusive results regarding lipid outcomes in individuals with prediabetes
        • Additional longer-term intervention studies are needed to ascertain the effects of relative reduction as well as low glycemic index/load values on lipid outcomes in individuals with prediabetes
        • Evidence is based on the following: Wolever and Mehling, 2003; Perala et al, 2011.
      • Anthropometric Outcomes (WC, WHR):
        • There were no studies identified to evaluate the relative reduction of glycemic index/load on anthropometric outcomes in individuals with prediabetes
        • Intervention studies are needed to ascertain the effects of relative reduction as well as low glycemic index/load values on anthropometric outcomes in individuals with prediabetes.
      • Blood pressure outcomes:
        • There were no studies identified to evaluate the relative reduction of glycemic index/load on blood pressure in individuals with prediabetes
        • Intervention studies are needed to ascertain the effects of relative reduction as well as low glycemic index/load values on blood pressure in individuals with prediabetes.

    • Recommendation Strength Rationale

      For Adults with Metabolic Syndrome

      • Grade III evidence is available for the conclusion statements regarding the impact of glycemic index/load, independent of weight loss, on the following outcomes:
        • Glycemic-related outcomes (such as fasting blood glucose, random blood glucose, two-hour post-prandial blood glucose, A1C)
        • Lipid (TG, HDL).
      • Grade V evidence is available for the conclusion statements regarding the impact of glycemic index/load, independent of weight loss, on the following outcomes:
        • Anthropometric measures (WC, WHR)
        • Blood pressure
        • Renal outcomes.

      For Individuals with Prediabetes

      • Grade III evidence is available for the conclusion statements regarding the impact of glycemic index/load, independent of weight loss, on the following outcomes:
        • Glycemic-related outcomes (such as fasting blood glucose, random blood glucose, two-hour post-prandial blood glucose, A1C)
        • Lipid (TG, HDL).
      • Grade V evidence is available for the conclusion statements regarding the impact of glycemic index/load, independent of weight loss, on the following outcomes:
        • Anthropometric measures (WC, WHR)
        • Blood pressure.
       

    • Minority Opinions

      Consensus reached.