88
VOLUME 10 NUMBER 3 • SEPTEMBER 2013
REVIEW
SA JOURNAL OF DIABETES & VASCULAR DISEASE
Is there an optimal diet for patients with type 2 diabetes?
Yes, the one that works for them!
Jeremy D Krebs, Amber Parry-Strong
Abstract
Diet is fundamental in the aetiology and management of
type 2 diabetes. The optimal diet remains unclear and the
EASD and ADA have recently adopted increased flexibility
with dietary composition, whilst maintaining a focus on
reduced energy, reduced saturated fat and increased dietary
fibre. This review draws three conclusions on the current
evidence for three dietary approaches; high protein diets,
very low carbohydrate diets and the Mediterranean diet,
specifically for the management of weight, glycaemic control
and cardiovascular risk in patients with type 2 diabetes. First,
unless energy intake is reduced below energy expenditure
over a sustained period of time, weight loss will not occur.
Second, weight loss achieved with any dietary approach over
the long-term is modest, though compared with the natural
history of weight gain in obesity is clinically important. Third,
the evidence supports flexibility in dietary composition with
no approach superior to another for weight loss, glycaemic
control or cardiovascular risk management. Most importantly
there is evidence that adherence to any given dietary approach
is more important than the macronutrient prescription. So the
best diet for those with type 2 diabetes is the one that works
for them, and critically the one that they can maintain in the
long term.
Keywords:
Diabetes mellitus, type 2, randomised controlled
trial, diet, carbohydrate-restricted, weight loss
Background
Type 2 diabetes (T2DM) is a complex andmultifactorial disease which
is defined by abnormalities in circulating glucose concentrations, or
more recently HbA
1c
, a measure of long term glycaemic burden.
1
A family history of T2DM, obesity, sedentary lifestyle and dietary
saturated fat are the key risk factors for the development of T2DM.
The pathogenesis is still not completely understood despite decades
of research. However, both abnormalities in insulin production and/
or release and impairment of insulin action are required before
diabetes ensues.
Diet is fundamental in the aetiology and the management of
T2DM. Energy intake is a critical component of energy balance and
body weight. Specific dietary components are implicated in diabetes
Correspondence to: Dr Jeremy Krebs
Endocrine, Diabetes and Research Centre, Capital and Coast Health,
Department of Medicine, University of Otago, Wellington, New Zealand.
e-mail:
Originally in:
Br J Diabetes Vasc Dis
2013;
13
(2): 60–66
S Afr J Diabetes Vasc Dis
2013;
10
: 88–92
Abbreviations:
ADA American Diabetes Association
CVD
cardiovascular disease
EASD
European Association for the Study of
Diabetes
HC
High carbohydrate
HP
High protein
LC
Low carbohydrate
T2DM
Type 2 diabetes mellitus
pathogenesis and manipulation of these mooted as means to modify
both weight and metabolic parameters. Thus whilst diet and lifestyle
modification are the cornerstone of the management of type 2
diabetes, despite an enormous amount of research the optimal
approach for this has not been defined. This is reflected in the dietary
recommendations from the EASD and the ADA which have both
recently adopted increased flexibility with dietary composition, whilst
maintaining a focus on reduced energy, reduced saturated fat and
increased dietary fibre.
1,2
Furthermore achieving sustained changes
in diet and lifestyle remain a significant challenge for patients
and healthcare professional alike. This review will focus on what
the current evidence is for three of the many dietary approaches
(Table 1), specifically for the management of weight, glycaemic
control and cardiovascular risk in patients with T2DM.
Historic recommendations for diet and type 2 diabetes
The earliest dietary treatment for T2DM, prior to the availability
of antidiabetic agents, was to restrict carbohydrate in the hope of
reducing the demand on endogenous insulin.
3
Even in the 1970s
Truswell
et al.
reported froma survey of clinics in the United Kingdom
that 92% of overweight people with T2DM were prescribed a low
carbohydrate diet.
4
Around this time research groups were starting
to experiment with high complex or unrefined carbohydrate diets
that were lower in total fat, higher in polyunsaturated fats and
included large quantities of fibre (up to 105 g per day).
5–7
This
type of diet, later known as the “high carbohydrate–low fat” diet,
was shown to be as good as or better than a low carbohydrate
Table 1.
Typical macronutrient comparison of popular diets.
Diet
Carbohydrate
(%TE)
Protein
(%TE)
Fat
(%TE)
Other
High protein
40
30
30
Very low carbohy-
drate, high fat
10
40
50
High carbohydrate,
High fibre
55
15
30 Fibre ≥
30 g
Mediterranean
45–55
15
30–40 High fibre
High MUFA
