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Recommendations Summary

PDM: Weight Loss 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: Weight Loss and Prevention of Type 2 Diabetes

    • For individuals who are at high risk for type 2 diabetes who are overweight or obese, the registered dietitian nutritionist (RDN) should prescribe a weight-reducing diet and support weight loss using evidence-based nutrition practice guidelines
    • In adults with metabolic syndrome, research regarding a weight loss achieved via lifestyle modification over at least a three-month period ranging from 1.1kg to 13kg reported significant improvements:
      • Decreased A1C by 0.12% to 0.3%
      • Decreased triglycerides by 20mg to 132mg per dL (0.23mmol to 1.5mmol per L)
      • Decreased waist circumference by 1.5cm to 11cm
      • Decreased systolic blood pressure by 4.9mm Hg to 10mm Hg.
    • In individuals with prediabetes, research regarding a weight loss achieved via lifestyle modification over at least a three-month period ranging from 2.6kg to 7.1kg reported significant improvements:
      • Decreased fasting glucose levels by 2.2mg to 9.2mg per dL (0.12mmol to 0.5mmol per L)
      • Decreased triglyceride levels by 30.9mg per dL (0.35mmol per L)
      • Decreased waist circumference by 1.3cm to 5.9cm
      • Decreased systolic blood pressure 3.5mm Hg to 6mm Hg and diastolic blood pressure by 5mm Hg.
    • In individuals with prediabetes, research regarding a weight loss achieved via bariatric surgery of up to 47kg or 41% of excess BMI over a period of three to five years reported significant improvements:
      • Decreased fasting glucose levels by 16.2mg to 20.9mg per dL (0.9mmol to 1.16mmol per L)
      • Decreased two-hour post-prandial glucose levels by 16mg per dL (0.9mmol per L)
      • Decreased A1C by 0.5%.
      • Decreased triglyceride levels by 70.6mg per dL (0.8mmol per L)
      • Increased HDL cholesterol levels by 1.9mg per dL (0.05mmol per L)
      • Decreased systolic blood pressure by 6mm Hg.

    Rating: Strong
    Conditional

    • Risks/Harms of Implementing This Recommendation

      • Reduction of caloric intake may result in nutritional inadequacies; therefore, special attention should be paid to maintaining adequate intake of vitamins and minerals
      • Adverse risks may be associated with pharmacotherapy and bariatric surgery.

    • Conditions of Application

    • Potential Costs Associated with Application

      The costs of medical nutrition therapy (MNT).

    • Recommendation Narrative

      A total of 28 studies (30 publications) were included in the evidence analysis for this recommendation:

      • Twelve positive-quality randomized controlled trials (RCT) (Lee et al, 2009; Al-Sarraj et al, 2010; Klemsdal et al, 2010; Straznicky et al, 2010; Busnello et al, 2011; Christian et al, 2011; Gagnon et al, 2011; Lu et al, 2011; Munakata et al, 2011; Sakane et al, 2011; Straznicky et al, 2011; Straznicky et al, 2012)
      • Nine neutral-quality randomized controlled trials (RCT) (Chan et al, 2008; Burtscher et al, 2009; Ng et al, 2009; Yassine et al, 2009; Mujica et al, 2010; Oh et al, 2010; Parikh et al, 2010; Katula et al, 2011; Seligman et al, 2011)
      • Two positive-quality cohort studies (Caiazzo et al, 2010; de la Cruz-Munoz et al, 2011)
      • Two neutral-quality cohort studies (Allen et al, 2008; Bihan et al, 2009)
      • One neutral-quality case-control study (Aizawa et al, 2009)
      • Three neutral-quality non-randomized controlled trials (Cicero et al, 2009; Kim et al, 2009; Evangelou et al, 2010)
      • One positive-quality systematic review (Orozco et al, 2008).

      In Adults with Metabolic Syndrome

      • Glycemic-related outcomes (FBG, random BG, two-hour post-prandial BG, A1C):
        • Most studies reported no significant impact of weight loss on fasting glucose levels in adults with metabolic syndrome. However, of two intervention studies reporting A1C values, both demonstrated that weight loss significantly reduced A1C by 0.12% to 0.3%
        • Additional longer-term intervention studies are needed to ascertain an effect of weight loss 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: Chan et al, 2008; Aizawa et al, 2009; Bihan et al, 2009; Cicero et al, 2009; Kim et al, 2009; Lee et al, 2009; Ng et al, 2009; Yassine et al, 2009; Evangelou et al, 2010; Mujica et al, 2010; Oh et al, 2010; Straznicky et al, 2010; Busnello et al, 2011; Christian et al, 2011; Munakata et al, 2011; Straznicky et al, 2011; Straznicky et al, 2012.  
      • Lipid outcomes (TG, HDL):
        • The majority of research reported that a weight loss ranging from 1.1kg to 13kg significantly reduced triglyceride levels by 20mg to 132mg per (0.23mmol to 1.5mmol per L) in adults with metabolic syndrome
        • Most studies reported no significant impact of weight loss on HDL cholesterol levels in adults with metabolic syndrome
        • Evidence is based on the following: Chan et al, 2008; Aizawa et al, 2009; Bihan et al, 2009; Cicero et al, 2009; Kim et al, 2009; Lee et al, 2009; Ng et al, 2009; Yassine et al, 2009; Al Sarraj et al, 2010; Evangelou et al, 2010; Mujica et al, 2010; Oh et al, 2010; Straznicky et al, 2010; Busnello et al, 2011; Christian et al, 2011; Munakata et al, 2011; Straznicky et al, 2011; Straznicky et al, 2012. 
      • Anthropometric outcomes (WC, WHR):
        • Research reports that a weight loss ranging from 1.1kg to 13kg significantly reduced waist circumference by 1.5cm  to 11cm in adults with metabolic syndrome
        • However, most studies reported no significant impact of weight loss on waist-to-hip ratio in adults with metabolic syndrome
        • Evidence is based on the following: Chan et al, 2008; Aizawa et al, 2009; Bihan et al, 2009; Kim et al, 2009; Lee et al, 2009; Ng et al, 2009; Yassine et al, 2009; Evangelou et al, 2010; Klemsdal et al, 2010; Mujica et al, 2010; Oh et al, 2010; Straznicky et al, 2010; Busnello et al, 2011; Christian et al, 2011; Munakata et al, 2011; Seligman et al, 2011; Straznicky et al, 2011; Straznicky et al, 2012.
      • Blood pressure outcomes:
        • Most studies reported that a weight loss ranging from 1.1kg to 8.4kg significantly reduced systolic blood pressure by 4.9mm Hg to 10mm Hg in adults with metabolic syndrome
        • However, the research regarding weight loss reports mixed results on diastolic blood pressure in adults with metabolic syndrome
        • Additional longer-term intervention studies are needed to ascertain an effect of weight loss on blood pressure in adults with metabolic syndrome with or without meeting the metabolic syndrome criteria for blood pressure
        • Evidence is based on the following: Chan et al, 2008; Aizawa et al, 2009; Bihan et al, 2009; Kim et al, 2009; Yassine et al, 2009; Evangelou et al, 2010; Mujica et al, 2010; Oh et al, 2010; Straznicky et al, 2010; Christian et al, 2011; Munakata et al, 2011; Straznicky et al, 2011; Straznicky et al, 2012.
      • Renal outcomes:  
        • Two intervention studies regarding the impact of weight loss on renal outcomes reported inconclusive results
        • Additional longer-term intervention studies are needed to ascertain an effect of weight loss on renal outcomes in adults with metabolic syndrome with or without meeting the metabolic syndrome criteria for urinary albumin excretion rate or albumin:creatinine ratio
        • Evidence is based on the following: Seligman et al, 2011; Straznicky et al, 2011.

      In Individuals with Prediabetes

      • Glycemic-related outcomes (FBG, random BG, two-hour post-prandial BG, A1C):
        • The majority of lifestyle modification intervention studies reported that weight loss significantly reduces fasting blood glucose in individuals with prediabetes, while most studies report no significant impact of weight loss on two-hour post-prandial blood glucose or A1C
        • Of those studies reporting a weight loss ranging from 2.6kg to 7.1kg, there was a significant reduction in fasting blood glucose levels by 2.2mg to 9.2mg per dL (0.12mmol to 0.5mmol per L)
        • In bariatric surgery intervention studies, a weight loss of up to 47kg or 41% of excess BMI over a period of three to five years significantly reduced fasting glucose levels by 16.2mg to 20.9mg per dL (0.9mmol to 1.16mmol per L), two-hour glucose levels by 16mg per dL (0.9mmol per L) and A1C by 0.5%
        • Additional lifestyle modification intervention studies are needed to ascertain the effects of weight loss on two-hour post-prandial blood glucose and A1C in individuals with prediabetes
        • Evidence is based on the following: Allen et al, 2008; Orozco et al, 2008; Burtscher et al, 2009; Caiazzo et al, 2010; Parikh et al, 2010; de la Cruz-Munoz et al, 2011; Gagnon et al, 2011; Katula et al, 2011; Lu et al, 2011, Sakane et al, 2011.
      • Lipid outcomes (TG, HDL):
        • Most lifestyle modification intervention studies reported that weight loss improves triglyceride levels, but does not have a significant impact on HDL cholesterol levels, in individuals with prediabetes
        • In the study reporting a weight loss of 2.7kg, there was a significant reduction in triglyceride levels by 30.9mg per dL (0.35mmol per L)
        • In one bariatric surgery intervention study, a weight loss of up to 41% of excess BMI significantly decreased triglyceride levels by 70.6mg per dL (0.8mmol per L) and increased HDL cholesterol levels by 1.9mg per dL (0.05mmol per L)
        • Additional lifestyle modification intervention studies are needed to ascertain the effects of weight loss on lipid outcomes in individuals with prediabetes
        • Evidence is based on the following: Allen et al, 2008; Orozco et al, 2008; Burtscher et al, 2009; Caiazzo et al, 2010; Gagnon et al, 2011; Lu et al, 2011, Sakane et al, 2011.
      • Anthropometric outcomes (WC, WHR):
        • The majority of lifestyle modification intervention studies reported that weight loss significantly reduces waist circumference, but does not have a significant impact on waist-to-hip ratio, in individuals with prediabetes
        • Of those studies reporting a weight loss ranging from 2.7kg to 7.1kg, there was a significant reduction in waist circumference by 1.3cm to 5.9cm
        • Evidence is based on the following: Allen et al, 2008; Orozco et al, 2008; Parikh et al, 2010; Gagnon et al, 2011; Katula et al, 2011; Lu et al, 2011, Sakane et al, 2011.
      • Blood pressure outcomes:
        • Most lifestyle modification intervention studies reported that weight loss significantly reduces systolic and diastolic blood pressure in individuals with prediabetes
        • Of those studies reporting a weight loss ranging from 2.7kg to 4.9kg, there was a significant reduction in systolic blood pressure of 3.5mm Hg to 6mm Hg and in diastolic blood pressure of 5mm Hg
        • In one bariatric surgery intervention study, a weight loss of up to 41% of excess BMI significantly reduced systolic blood pressure by 6mm Hg
        • Evidence is based on the following: Allen et al, 2008; Orozco et al, 2008; Burtscher et al, 2009; Caiazzo et al, 2010; Parikh et al, 2010; Gagnon et al, 2011; Lu et al, 2011, Sakane et al, 2011.

    • Recommendation Strength Rationale

      For Adults with Metabolic Syndrome

      • Grade I evidence is available for the conclusion statements regarding the impact of weight loss for at least a three-month period on the following outcomes:
        • Lipid (TG, HDL)
        • Anthropometric measures (WC, WHR).
      • Grade II evidence is available for the conclusion statements regarding the impact of weight loss for at least a three-month period on the following outcomes:
        • Glycemic-related outcomes (such as fasting blood glucose, random blood glucose, two-hour post-prandial blood glucose, A1C)
        • Blood pressure.
      • Grade III evidence is available for the conclusion statements regarding the impact of weight loss for at least a three-month period on the following outcomes: Renal outcomes.

      For Individuals with Prediabetes

      • Grade I evidence is available for the conclusion statements regarding the impact of weight loss for at least a three-month period on the following outcomes:
        • Glycemic-related outcomes (such as fasting blood glucose, random blood glucose, two-hour post-prandial blood glucose, A1C)
        • Anthropometric measures (WC, WHR)
        • Blood pressure.
      • Grade II evidence is available for the conclusion statements regarding the impact of weight loss for at least a three-month period on the following outcomes: Lipid (TG, HDL).

    • Minority Opinions

      Consensus reached.