Five randomized controlled trials (Barriocanal et al 2008, Maki et al, 2008, Ferri et al, 2006, Gregerson et al, 2004, Hsieh et al, 2003) examined the effects of stevia compared to placebo on metabolic outcomes or weight and reported minimal, if any effects, on blood glucose and insulin levels, hypertension and weight. However, the majority of the trials were of small sample size and used varying doses of stevia.

One trial (Barriocanal 2008) in subjects with type 1 or type 2 diabetes or without diabetes reported no significant (NS) changes from baseline in serum glucose or HbA1C levels. However, one trial (Gregerson 2004) in subjects with type 2 diabetes reported a reduced postprandial blood glucose and glucagon response after a test meal of stevia vs. placebo. In subjects without diabetes, one trial (Ferri 2006) reported both glucose and insulin reductions in both the stevia and placebo groups.

Two trials (Barriocanal 2008, Maki 2008) in subjects with normal/low blood pressure (BP) detected NS changes from baseline in BP from stevioside compared to controls. In subjects with Stage 1 hypertension (HTN) no anti-hypertensive effects of stevioside compared to placebo were found (Ferri 2006). A third study (Gregerson 2004) also reported no changes in BP from stevioside compared to placebo. However, a two-year trial in Chinese subjects with mild HTN reported decreases in BP from stevia compared to placebo (Hsieh 2002).

Only one trial studied weight change and reported no change (Hsieh 2003).

• Grade I means there is Good/Strong evidence supporting the statement;
• Grade II is Fair;
• Grade III is Limited/Weak;
• Grade IV is Expert Opinion Only;
• Grade V is Not Assignable.
• High (A) means we are very confident that the true effect lies close to that of the estimate of the effect;
• Moderate (B) means we are moderately confident in the effect estimate;
• Low (C) means our confidence in the effect estimate is limited;
• Very Low (D) means we have very little confidence in the effect estimate.
• Ungraded means a grade is not assignable.