www.The-RDS.org 26 DOI 10.1900/ RDS.2010.7.26
The Review of
The Role of Diet and Lifestyle in Primary, Secondary, and
Tertiary Diabetes Prevention: A Review of Meta-Analyses
1, Ioannis Ilias
2 and Maria Alevizaki
1Department of Hygiene, Epidemiology and Medical Statistics, School of Medicine, University of Athens, Greece.
crinology, Diabetes and Metabolism, Elena Venizelou Hospital, Athens, Greece.
Athens University School of Medicine, Alexandra Hospital, Athens, Greece.
Address correspondence to: Theodora Psaltopoulou, e-mail: firstname.lastname@example.org
2Department of Endo-
3Endocrine Unit, Department of Clinical Therapeutics,
Prevention of diabetes is crucial to lowering disease inci-
dence, and thus minimizing the individual, familial, and pub-
lic health burden. The purpose of this review is to gather
current information from meta-analyses on dietary and life-
style practices concerning reduction of risk to develop type 2
diabetes. Low glycemic index dietary patterns reduce both
fasting blood glucose and glycated proteins independent of
carbohydrate consumption. Diets rich in whole-grain, cereal
high fiber products, and non-oil-seed pulses are beneficial.
Whereas, frequent meat consumption has been shown to
increase risk. Regarding non-alcoholic beverages, 4
cups/day of filtered coffee or tea are associated with a re-
duced diabetes risk. In contrast, the consumption of alco-
holic beverages should not exceed 1-3 drinks/day. Intake of
Manuscript submitted November 10, 2009; resubmitted February 4, 2010; accepted February 7, 2010
vitamin E, carotenoids, and magnesium can be increased to
counteract diabetes risk. Obesity is the most important fac-
tor accounting for more than half of new diabetes’ cases;
even modest weight loss has a favorable effect in preventing
the appearance of diabetes. Also, physical exercise with or
without diet contributes to a healthier lifestyle, and is impor-
tant for lowering risk. Finally, there is a positive association
between smoking and risk to develop type 2 diabetes. As far
as secondary and tertiary prevention is concerned, for per-
sons already diagnosed with diabetes, there is limited evi-
dence of the effectiveness of diet or lifestyle modification on
glycemic control, but further studies are necessary.
Keywords: type 2 diabetes · diet · lifestyle · nutrition ·
physical activity · weight loss · glycemic control · meta-
analysis · diabetes prevention
enes and environment can interact to cause
chronic diseases such as type 2 diabetes. In
older age-groups, diabetes has reached epi-
demic numbers, and the epidemic is expected to
continue to grow. This is mainly due to an increas-
ing proportion of aged people in the worldwide
population . Other aggravating factors are obe-
sity in general, and increased ratios of abdominal
fat distribution . It is considered that more than
half (60-90%) of new cases are due to obesity and
weight gain . Certainly, unhealthy diet and life-
style can impose an additional burden on good gly-
cemic control in diabetes patients.
Efforts to prevent diabetes are necessary, as
they could make a significant contribution to low-
ering the rate of new diabetic cases. Apart from
the benefits to the individual, they would reduce
the, familial, and public health burden caused by
the disease. Dietary habits are the personal deci-
sions individuals make when choosing their nutri-
tion. Nutrition therapy is generally recommended
for primary, secondary, and tertiary prevention.
Primary prevention means intervention before the
development of diabetes, secondary prevention re-
The Review ofDIABETIC STUDIES
Vol 7 No 1 2010
Role of Diet and Lifestyle in Diabetes The Review of DIABETIC STUDIES
Vol . 7 ⋅ No. 1 ⋅ 2010
www.The-RDS.org Rev Diabet Stud (2010) 7:26-35
fers to the time after diagnosis of diabetes, and
tertiary prevention can take place when signifi-
cant numbers of beta-cells remain after diagnosis.
Primary prevention is particularly important in
type 2 diabetes, because the time of diagnosis and
the severity of the disease course can be influ-
enced beneficially by changing daily lifestyle and
dietary practices. However, despite this aware-
ness, there is still no universal dietary approach
for diabetes prevention and management.
A multitude of reviews and meta-analyses have
been published during the last few years. They
summarize present knowledge and quantify dif-
ferences in effectiveness between different dietary
and lifestyle preventive measures. In contrast to
biological factors, which have an impact on physi-
cal health, lifestyle encompasses modifiable social
and behavioral factors . In respect to diabetes,
it is commonly limited to exercise, education, and
smoking cessation. In this review, we gather and
evaluate current information from meta-analyses
on dietary and lifestyle practices proposed for re-
ducing the risk of type 2 diabetes.
Materials and methods
English publication meta-analyses between the
years 2000 and 2009 were selected through a com-
puter-assisted literature search (i.e., Pubmed). We
used combinations of the following key words for
computer searches: “diabetes” and “diet” or “life-
style” and “meta-analysis”. Study selection was
restricted to meta-analyses to capture most of the
available study data, and to standardize and col-
lectively use the results of numerous case-control
and prospective studies. The included studies were
mainly randomized controlled trials to ensure that
the data to be used was of sufficiently high-
In addition, the reference lists of the retrieved
articles helped us to find further articles, relevant
to the present analysis that were not revealed
through the searching procedure. The followingin-
formation was abstracted according to a fixed pro-
tocol: name of the first author and year of publica-
tion, sample size, mean age, sex of participants,
follow-up duration when available, assay methods
and effect measures, and degree of adjustment for
potential confounders. For keywords “diabetes”
and “diet” and “meta-analysis” 116 papers were
retrieved. The publication dates raged from J anu-
ary 2000 to October 2009. For keywords “diabetes”
and “lifestyle” and “meta-analysis” 67 papers were
retrieved. They had the same publication date
range, J anuary 2000 to October 2009.
Of those articles initially identified, 40 were
considered relevant to the present study, and
these articles were finally included in the present
review. To qualify them as relevant, only those in
English language, dealing with diabetes type 2 in
adults were included. We excluded articles dealing
with diabetes prevention aided by pharmaceutical
treatments, and those analyzing genetic polymor-
phism. Articles looking at diabetes care exclu-
sively from a public health perspective, and those
dealing with subjects such as obesity in children,
colorectal and breast cancer, or renal disease were
also rejected from the analysis.
The analysis presented here is structured as
follows: the first section analyses food groups and
diabetes prevention. We have pooled articles on
this topic, because it is easier for individuals to
base their decisions on food groups rather than
specific ingredients. Subsequently, we looked at
micro- and macronutrients and risk of diabetes,
and finally we examined dietary patterns in rela-
tion to diabetes. The results are presented in Ta-
bles 1 and 2.
F ood groups and how they influence
Evidence is accumulating that whole-grain
products are beneficial to health, and protect
against chronic diseases (mainly cancer and car-
diovascular diseases). In a meta-analysis includ-
ing six cohort studies with 286,125 participants
and 10,944 cases, a two-serving-per-day increment
in whole grain intake was associated with a 21%
reduction in risk for type 2 diabetes (95% CI: 13%
to 28%), after adjusting for potential confounders
and body mass index .
Another large meta-analysis confirmed the
above results by showing reduced risk for type 2
diabetes with higher cereal fiber intake (RR for
extreme categories: 0.67, 95% CI: 0.62 to 0.72) .
Schulze and colleagues have speculated that both
insoluble and soluble fibers could play a role in
diabetes prevention. In the same paper, the au-
thors found that the intake of fruit (RR: 0.96; 95%
CI: 0.88 to 1.04) and vegetable fibers (RR: 1.04;
95% CI: 0.94 to 1.15) did not significantly reduce
the risk for type 2 diabetes . Also in accord with
these results, a meta-analysis including 167,128
participants and 4,858 incident cases of type 2
diabetes, with a mean follow-up period of 13 years,
showed that the consumption of fruit and vegeta-
bles provided no protection from type 2 diabetes
. Specifically, the relative risk was 1.01 (95%
Role of Diet and Lifestyle in Diabetes The Review of DIABETIC STUDIES
Vol . 7 ⋅ No. 1 ⋅ 2010
www.The-RDS.orgRev Diabet Stud (2010) 7:26-35
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