egetarian and total plant-based diets (vegan diet)
have gained much attention for their positive effects in promoting
healthy lives and in the prevention and treatment of
certain diseases (1-3). Conditions including obesity, diabetes
mellitus, dyslipidemia, atherosclerotic cardiovascular
disease, cancer, and a variety of gastrointestinal disorders
have been improved in persons consuming these diets
(2-4). Some of the aforementioned effects are secondary
to changes in multiple parameters, including reduction in
body weight, improved insulin sensitivity, modulation of
gut hormones, and decreased inflammation (2). Although it
is possible that many of the beneficial effects of vegetarian
and plant-based diets can be attributed to their high-fiber
content, the extent to which the contribution of fiber contained
in such foods is linked to the positive health outcomes
From the initial search strategy,22,046 studies were iden-
tified (Figure 1). Based on titles and abstracts, 45 studies
were selected for full-text examination. In addition, 15
studies were identified in the references lists of the
included studies and in the two previously published sys-
tematic reviews on the topic. None of the studies identi-
fied at www.clinicaltrials.gov (
n
=
51)andinthe
published ADA (
n
=
325) and EASD (
n
=
26) meeting
abstracts fulfilled the inclusion criteria for the current
review. Thus, 60 studies underwent full-text evaluation.
Among these 60 studies,11
18–28
fulfilled the inclusion
criteria. One study report
20
was included as three inde-
pendent reports because data were described according to
the type of diabetes treatment (i.e., diet only, insulin, or
oral antidiabetic drugs); thus, a total of 13 comparisons
were included in the analyses (Figure 1). All of the
included studies evaluated HbA1c changes and eight also
reported fasting plasma glucose as an outcome