Dietary Fat and Type 2 Diabetes

This study explores the connection between dietary fat intake and the prevention of type 2 diabetes. It examines the impact of different types of fats on the development of the disease and provides evidence on how dietary fats affect type 2 diabetes. The study utilizes a systematic review and includes various cohort studies to gather data on the association between dietary fat intake and type 2 diabetes.

Dietary Fat and Type 2 Diabetes 1
Dietary Fat and Prevention of Diabetes
Student’s Name
Course
Professor’s Name
University
City
Date

Dietary Fat and Type 2 Diabetes 2
Introduction
Type 2 diabetes, also known as Diabetes mellitus type 2, is a prolonged condition
affecting the way in which sugar is metabolized in a human body. It is characterized by insulin
resistance, high blood sugar and relative absence of sugar. It is normally revealed through certain
symptoms including frequent urination, increased thirst, unexpected weight loss and increased
vulnerability to infections especially fungal or yeast infections. Type 2 diabetes together with its
complexities constitutes a major universal public health issue that affects nearly all populations
in developing and developed countries. It is approximated that over 400 million people across
the world survives or lives with type 2 diabetes (Rice 2018). According to a research by Schmidt
et al. 2016, it is one of the four major diseases recognized by the World Health Organization as
the cause of mortality and morbidity and that needs to be focused on in order to prevent and
control it. In the past, type 2 diabetes was known as adult – onset diabetes, however, recently
more children have continued to be diagnosed with the disorder. It has become a serious and a
chronic disease that results from a complicated inheritance environment interaction alongside
other risks factors including sedentary lifestyle factors, gene and obesity (Wu et al, 2014).
Although the actual causes of Type 2 diabetes are still not totally understood, its main
cause is mainly linked with obesity or being overweight (Jorge, et al 2001). In addition, surplus
and excess body fat are as result of an imbalance energy intake and physical activity is the
primary risk factor for type 2 diabetes (National Institutes of Health (US)., 2007). A large body
investigational statistics produced in laboratory animals are strongly in support of the notion that
high – fat diets that results to obesity are linked with damaged insulin action. According to these
researches, it appears from these animals that saturated fats in precise contain the most
detrimental effects. Based on the research by Pan, et al. (2013) together with the already known

Dietary Fat and Type 2 Diabetes 3
risks of intake of high saturated fat on cardiovascular disease risk, specialized organizations
including the American Heart Association, American Diabetes Association and Agricultural
Department in U.S have given recommendations that Americans aim for a total intake of fat of
not more than 30% of calories choosing foods low in saturated fat (Office of the Surgeon
General (US); Office of Disease Prevention and Health Promotion (US); Centers for Disease
Control and Prevention (US); National Institutes of Health (US), 2001. However, some
researchers have criticized the basis of the evidence of these recommendations.
The objective of this paper is to investigate whether dietary fat intake helps in prevention
of type 2 diabetes. Since limited number of reviews has been carried out to investigate this
relationship, the current study will contribute to literature by compiling evidence on how dietary
fats affect type 2 diabetes.
Methods
A systematic review was conducted as the method of data collection. A systematic search
that began on March 2019 was carried out on electronic databases such as Pubmed, Cumulative
Index to Nursing and Allied Health Literature (CINAHL), and MEDLINE. The Population,
Intervention, Comparison, Outcome model was utilized to guide the search. Key words were
used together with Boolean operators ‘OR’ and AND’ to ensure more particular and productive
results were retrieved. The asterisk (*) was utilized together with truncated word ‘diet’. Other
key words used included ‘diabetes risk,’ ‘type 2 diabetes,’ ‘dietary fat,’ ‘diet* and type 2
diabetes,’ ‘dietary fat and type 2 diabetes,’ and diet* and ‘type 2 diabetes or diabetes mellitus.’
Also, the types of food known to contain the different types of fats were included such as ‘meat,’
‘dairy products,’ ‘olive oil,’ and ‘fish.’

Dietary Fat and Type 2 Diabetes 4
Inclusion and Exclusion Criteria
The current study included peer reviewed journals published between 2010 and 2019 to
ensure the retrieved evidence is current and of high quality. Empirical primary studies conducted
quantitatively or qualitatively were included while excluding expert opinions, news articles,
websites, audits, systematic reviews, and meta-analysis to ensure free from bias, high quality
evidence is obtained. Additionally, included studies were required to investigate the association
between intake of different foods containing dietary fat and development or prevention of type 2
diabetes in human population, specifically adults of either or both gender. Studies that
investigated the variables in other animals were excluded. The study was limited to resources
published in English or already translated into English with consideration to the review’s scope,
with no translation funding. Similarly, literature whose full text was available was used to allow
complete screening and information retrieval.
The eligibility criteria were applied to the literature in a screening process comprised of
two phases. The first phase involved reading of titles and abstracts of the retrieved literature
while comparing them against the set eligibility criteria. The literature that failed to meet the
predefined standards was excluded. Subsequently, the second stage entailed full text reading of
the remaining literature while eliminating studies that failed to meet the inclusion criteria. The
results of the search process are presented in the below modified PRISM diagram.

Dietary Fat and Type 2 Diabetes 5
Identification →
Literature identified
through database
searching (n= 569)
↓
Literature after removal of duplicates (n= 585)
↓
Screening,
Eligibility
Literature screened by title or
abstract (n= 585)
→ Literature excluded
(n= 542)
Literature screened by full-text
(n= 43)
→ Literature excluded
(n= 33)
↓
Included Total number of literature included for critical evaluation (n= 10)
Figure 1. Modified PRISMA depicting results of the search process
Data Extraction and Analysis
Data was extracted using an instrument established for the purposes of the current
research. Data analysis was performed by revisiting every chosen study for inclusion and looking
for information pertinent to the research question. Thematic analysis was used in data analysis

Dietary Fat and Type 2 Diabetes 6
where data was read and re-read to identify and sort the overriding and recurrent ideas revealed.
Thematic analysis was done manually.
Quality assessment
The respective CASP checklist was used to assess the quality of the included studies.
Depending on the number of questions answered “cannot say”, “no,” or yes the studies were
rated as high quality, low quality, or acceptable.
Since all the studies utilized prospective cohort design to investigate the effect of
different dietary fat on type 2 diabetes, the CASP checklist for cohort study was used. All the
studies were either acceptable or high quality in terms of the quality, with the most strengths
arising from sufficient period of follow up, controlling the influence of confounding factors by
including them in the multivariate logistic analysis, selection of fairly large cohorts, and
appropriate design considering the scope of the studies. However, potential weaknesses of most
studies arose from utilization of self reporting of dietary intake, an aspect that may have reduced
the internal quality of studies due to influence of response bias. Additionally, although some
confounding factors were controlled residual clustering and confounding of healthy behaviors
cannot be accounted for completely. What is more, external validity of the studies was threatened
since the study populations were from a single origin. As such, generalizabilty of findings to
other populations cannot be done.
Results
The following table is a summary of the studies included in this review.
Researc
h Study
Citation Aims Methods/
design
Sample /
Population
Findings

Dietary Fat and Type 2 Diabetes 7
RS1 O’Connor
, Luben,
&Wareha
m (2013).
To
investigate
if dairy Fat
increases
Incident
Diabetes
Mellitus in
united states
Prospectiv
e cohort
combined
by meta-
analysis
2 large US
Nurses’ Health
Study and
Health
Professionals
Follow-Up
Study (HPFS)
3333participant.
(n=166),exclud
ed .1364
participants
with CVD
1969 without
CVD
High dietary fat was
linked with lower
incident type 2
diabetes
RS2 Pan, et al.
(2013)
To
determine if
type 2
diabetes was
associated
with
consumptio
n of red
meat
prospectiv
e cohort
studies
26,357 menin
the Health
Professionals
Follow-up
Study (1986-
2006)
48,709
womenin the
Nurses' Health
Study(1986-
2006)
74,077 women
in the
Nurses'Health
Study II (1991-
2007)
Increasing the intake
of red meat was
linked with
increased risk of
Type 2 diabetes and
the association is
partially interceded
by weight of the
body.
RS3 Guasch-
Ferré, et al
(2015)
To examine
the
connection
between
olive oil
intake and
type 2
diabetes
2
prospectiv
e cohort
studies
59,930 women
from the
Nurses'Health
Study (NHS)
between 37 and
65years of age
and 85,157
from the NHS II
aged between
26 and 45 y
Were followed.
It was determined
that higher intake of
olive oil is linked
with modestly
reduced risk of type
2 diabetes.
RS4 Pan, et al.
(2011)
To evaluate
the
relationship
between
processed
3
prospectiv
e cohorts
studies
37,083 men in
the Health
Professionals
Follow-Up
Study (1986-
Indicated that
consumption of red
meat mainly the
processed is linked
with augmented

Dietary Fat and Type 2 Diabetes 8
and
unprocessed
red meat
consumptio
n and type 2
diabetes
2006), 79,570
women in the
Nurses'Health
Study I (1980-
2008), and
87,504 women
in the
Nurses'Health
Study II (1991-
2005).
danger of type 2
diabetes
RS5 Guasch-Ferré,
et al. (2017)
To
investigate
connection
between
baseline and
a year
challenge in
acylcarnitin
es and their
ability to
project
diabetes
prospectiv
e cohorts
study
694 randomly
selected
participants
including all
incident cases
of type 2
diabetes(n =
251)
An acylcarnitine
profile, mainly
comprising short-
and long-chain
acylcarnitines, was
considerablyconnect
ed with higher T2D
risk
RS6 Mari-Sanchis,
et al. (2016)
Assessing
the risks of
developing
type 2
diabetes in
associated
with meat
consumptio
n
prospectiv
e cohorts
study
18,527
participants
were observed
in the
SUNproject
students who
were graduates.
The results
suggested that meat
intake, specially
processed meat, was
linked with a
elevated risk of
developing diabetes
RS7 Rylander,
Sandanger,
Engeset, &
Lund (2014)
Examining
the risk of
T2DM in
connection
to
consumptio
n of lean
fish, fatty
fish, fish
products and
entire fish as
well as cod
liver oil
supplements
in
prospectiv
e
population
based
cohort
study
33740 women
free of T2DM,
stroke, and
heart attack and
with
thoroughinfo on
significant co-
variates and
dietary intake at
baseline.
Lean fish
consumption had
beneficial effect on
T2DM. It remained
uncertain whether
lean fish in itself has
a protective effect on
T2DM or that lean
fish consumers have
a protective life-style
that we were not
able to take into
account in this study.
were not observed

Dietary Fat and Type 2 Diabetes 9
Norwegian
women.
RS8 Sluijs, I et al.
(2012),
Assess the
connection
between
total dairy
products and
T2DM
Nested
case
cohort
1073 non-
diabetic
participants
No association was
indicate between
dietary fat and
T2DM
RS9 Talaei, Wang,
Yuan, Pan, &
Koh (2017)
To evaluate
the
connections
of, poultry,
fish, red
meat and
shellfish
intakes and
the risk of
type 2
diabetes
mellitus
cohort
study
63,257 Chinese
adults from
1993 to 1998
Red meat and
poultry consumption
was linked with a
increased risk of
T2D.
RS10 Pan, Sun,
Manson,Willet
t, & Hu
(2013).
examine the
association
between
walnut
consumptio
n and
incident
type 2
diabetes
cohort
study
79,893 women
in NHS II
(1999-2009)
and 58,063
women in NHS
(1998-2008)
with no chronic
disease at
baseline
Elevated walnut
utilization is
associated with a
significantly
decreased risk of
type 2 diabetes in
women.
Table 1. Summary of studies included
Findings of the current study are presented in themes emerging from the included studies during
thematic analysis.
Dietary Dairy Product Intake and Type 2 Diabetes
The association between total as well as types of dairy products and development of
diabetes was investigated in RS1, RS5, and RS8. Findings of all the three studies revealed that
consumption of total dairy products was not related with type 2 diabetes. RS8 and RS5 revealed
that intake of cheese and whole –fat yoghurt respectively had an inverse relationship with type 2

Dietary Fat and Type 2 Diabetes 10
diabetes. RS8’s findings contradict those revealed in RS5 who found that intake of butter and
cheese was linked to higher risk of type 2 diabetes (T2D). With regard to RS1, findings
suggested that no association exists between milk, high fat fermented dairy products, and cheese.
Additionally, RS8 found out that higher combined consumption of fermented dairy products was
inversely correlated with diabetes. RS5 revealed that yearly updated consumption of dairy
products was related with high risk of T2D.
Red Meat Consumption and Type 2 Diabetes
The association between red meat consumption and risk of T2D was investigated in RS2,
RS4, RS6, RS9, and RS5. All findings were consistent that intake of red meat is associated with
increased risk of T2D. RS4 and RS9 investigated the effect of processed meat on T2D and
revealed that a positive association exists between these variables.
Intake of Olive Oil, Butter, Stick Margarine, and Mayonnaise and Type 2 Diabetes
RS3 revealed that in comparison to intake of butter, stick margarine, and Mayonnaise,
consumption of olive oil reduces the risk of developing T2D.
Fish Intake and Type 2 Diabetes
This theme was featured in RS5, RS7, RS8, and RS9. RS7 indicated that fatty fish, total
fish, fish products, and intake of cod liver oil supplement do not affect the risk of developing
T2D. These findings were consistent with those in RS5, RS8, and RS9 who revealed that intake
of fish is not associated with T2D. These studies did not specifically investigate lean fish. RS7
found out that lean fish intake was inversely related with T2D in comparison to zero intake.
Consumption of Walnuts and Type 2 Diabetes

Dietary Fat and Type 2 Diabetes 11
In RS10, consumption of walnut was found to reduce the risk of developing T2D.
According to RS5, yearly updated consumption of nuts was found to be strongly and positively
associated with T2D.
Discussion
The current study sought to investigate the association between dietary fat and type 2
diabetes as a way of determining the role these fats can play in preventing or causing the disease.
To meet this aim, a systematic review of literature was conducted and 10 peer reviewed journals
were retrieved and used as evidence. Representative common foods of different types of fats
were used. More precisely, olive oil (monounsaturated fat), fish and walnuts (polyunsaturated
fats), and meat and dairy products (saturated fats) were investigated. Results indicated that a
strong association between red meat, walnut, and olive oil and T2D exists. On the other hand,
fish intake and type 2 diabetes were not associated. With regard to the association between
dietary dairy products and T2D, findings were inconclusive with findings ranging from no
association to positive and negative relationship.
The lack of association between fish consumption and T2D has been supported by Xun
and He (2012) whose meta-analysis concluded that indicated that their study failed to provide
evidence that there is an inverse association between the two variables. Similarly, the findings of
the current study are inconsistent with those of Zhou, Tian, & Jia (2012) who suggested that
intake of fish increases the risk for type 2 diabetes development.
Findings that red meat increases the risk for type 2 diabetes have been supported by prior
studies. According to Barnard, Levin, and Trapp (2014)’s meta-analysis increase in meat intake
increases the risk of development of type 2 diabetes. However, Derbyshire & Ruxton (2015)’s

Dietary Fat and Type 2 Diabetes 12
systematic review indicates that the effect of red meat on T2D is weak and attenuates when
certain factors are controlled.
The varying and inconsistent results on the association between dietary fats and risk for
type 2 diabetes can be attributed to the different communities included in the current review. In
the eligibility criteria, no restriction was imposed to ensure retrieval of studies from the same
regions; as a result, studies included had investigated participants in different locations. As
Bradley (2018) outlines, variation in effects of dietary fats may vary with geographic locations
and communities.
The study suggests that the benefits of dietary fats depend on the type of specific fat, with
some having the ability to reduce the risk of developing type 2 diabetes. The importance of
considering the sub types of food groups in messages seeking to promote public health is also
suggested in the current study.
Conclusion
The study revealed that total dietary fat and fish consumption are not associated with risk
of type 2 diabetes but with red meat, walnut, and olive oil the relationship between the variables
is strong. Thus, from a point of view of public health, reducing consumption of red meat and
dairy products and replacing it with consumption of walnut, specific dairy products, and olive oil
can help prevent occurrence of type 2 diabetes. However, more studies should be conducted to
verity the results of the current study.

Dietary Fat and Type 2 Diabetes 13
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Dietary Fat and Type 2 Diabetes 14
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Dietary Fat and Type 2 Diabetes 15
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Dietary Fat and Type 2 Diabetes 16
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