Effects and clinical potential of very-low-calorie diets (VLCDs) in type 2 diabetes.

Abstract

A recent study has shown that obese patients with newly diagnosed type 2 diabetes who lose 10% of their body weight are more likely to achieve glycaemic and blood pressure targets, despite weight regain. A well-established non-surgical method for achieving weight loss >or=10% within 3 months is the use of very-low-calorie diets (VLCDs). In patients with diabetes, VLCDs are associated with rapid improvement in glycaemia and cardiovascular risk factors. The present review analyses the evidence from available trials on the effects of VLCDs on body weight, glycaemic control and complications, and their potential for clinical use in diabetes management.

Full text

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Review
Effects and clinical potential of very-low-calorie diets (VLCDs)
in type 2 diabetes§,§§
Scott Baker*, George Jerums, Joseph Proietto
Department of Medicine, Austin Health, University of Melbourne, Heidelberg Repatriation Hospital, 300 Waterdale Road,
West Heidelberg, VIC 3081, Australia
Contents
1.
2.
3.
4.
5.
6.
7.
8.
Weight loss as a treatment for type 2 diabetes (T2D). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VLCDs as a weight loss intervention in obesity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VLCDs and diabetes prevention . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VLCDs as a weight loss intervention in T2D. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VLCDs effect on glycaemia in T2D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
VLCDs on cardiovascular risk factors in T2D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Current recommendations for the use of VLCDs in T2D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Further research in VLCDs and T2D . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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diabetes research and clinical practice xxx (2009) xxx–xxx
a r t i c l e i n f o
Article history:
Received 23 December 2008
Received in revised form
30 April 2009
Accepted 2 June 2009
Keywords:
Very-low-calorie diets
Type 2 diabetes
Weight loss
a b s t r a c t
Arecentstudyhasshownthatobesepatientswithnewlydiagnosedtype2diabeteswholose
10% of their body weight are more likely to achieve glycaemic and blood pressure targets,
despite weight regain. A well-established non-surgical method for achieving weight loss
?10% within 3months isthe use of very-low-caloriediets (VLCDs). Inpatients with diabetes,
VLCDs are associated with rapid improvement in glycaemia and cardiovascular risk factors.
The present review analyses the evidence from available trials on the effects of VLCDs on
body weight, glycaemic control and complications, and their potential for clinical use in
diabetes management.
# 2009 Elsevier Ireland Ltd. All rights reserved.
§Grant support/declarations: Scott Baker has received funding from Pfizer CVL grants and the National Health & Medical Research
Council of Australia. Joseph Proietto is Chair of the Optifast Medical Advisory Committee for Nestle Nutrition. Nestle Nutrition are
currently providing subsidised Optifast VLCD for ongoing clinical trials through University of Melbourne/Austin Health.
§§This review was presented at the Australian Diabetes Society Annual Scientific Meeting in Melbourne, Australia, August 2008. Baker
S.T. The use of very-low-calorie diets (VLCDs) in type 2 diabetes. Australian Diabetes Society and Australian Diabetes Educators
Association Annual Scientific Meeting Proceedings (2008). Abstract 7.
* Corresponding author at: Endocrine Centre, Austin Health, P.O. Box 5444, West Heidelberg, VIC 3081, Australia. Tel.: +61 394965489.
E-mail address: scott.baker@austin.org.au (S. Baker).
0168-8227/$ – see front matter # 2009 Elsevier Ireland Ltd. All rights reserved.
doi:10.1016/j.diabres.2009.06.002
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Please cite this article in press as: S. Baker, et al., Effects and clinical potential of very-low-calorie diets (VLCDs) in type 2 diabetes,
Diab. Res. Clin. Pract. (2009), doi:10.1016/j.diabres.2009.06.002
Contents lists available at ScienceDirect
Diabetes Research
and Clinical Practice
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1.
diabetes (T2D)
Weight loss as a treatment for type 2
Obesity is the major risk factor for type 2 diabetes (T2D),
accounting for 60–90% of cases [1]. Approximately 80% of
people with T2D are overweight or obese, and obesity
compounds the cardiovascular risk of T2D, such that T2D
individuals 20–30% above their ideal body weight have 2.5–3-
fold higher mortality compared to people with diabetes at
their ideal weight. Mortality rises to greater than fivefold for
individuals >40% above their ideal weight [1]. Weight loss
produces numerous benefits in T2D including improved
glucose metabolism, reduction in glycaemia and fasting
insulin levels and increased insulin sensitivity, reduction in
blood pressure, and improvements in lipid profile with
decreased triglycerides, increased high density lipoprotein
cholesterol (HDL-C) and fewer small, dense low density
lipoprotein cholesterol (LDL-C) particles [2]. Observational
data suggest weight loss increases life expectancyin T2D by 3–
4 months per kilogram lost [3].
Large weight losses (e.g. 10% or more of the baseline body-
weight), such as with bariatric surgery, can lead to marked
improvements in or remission of T2D [4]. A randomised study
inrecentlydiagnosedobeseT2Dpatientsshowedlaparoscopic
adjustable gastric banding is superior to conventional lifestyle
intervention in achieving remission of diabetes at 2 years,
largely due to the degree of weight loss (20.7% versus 1.7%) [5].
In the absence of surgical intervention, a retrospective cohort
study in 2574 people with newly diagnosed T2D found that
thosewholostcloseto10%oftheirbodyweightafterdiagnosis
were more likely to achieve glycaemic and blood pressure
targets despite weight regain by year 4, compared to patients
who maintained their weight or gained weight post-diagnosis
[6].WeightlossseemsmoreachievableinT2Dpatientsearlyin
their disease [7], and one large study investigating intensive
lifestyle intervention and major cardiovascular events is
ongoing [2].
2.
obesity
VLCDs as a weight loss intervention in
Very-low-calorie diets (VLCDs) are defined as diets limiting
energy intake to 1.88–3.35 MJ (450–800 kcal) per day while
providing atleast 50 g of high-quality protein and amino acids,
essential fatty acids and daily requirements of trace elements,
vitamins and minerals. They are recommended only in the
obese(bodymassindex(BMI)?30 kg/m2)orinindividualswith
BMIs >27 kg/m2plus one or more co-morbidities. Generally,
they involve an intensive phase (three meal replacements)
usually lasting 8–16 weeks. In addition, two cups of salad or
low-starch vegetables are eaten to provide fibre to lessen
hunger and reduce constipation [8]. A tablespoon of oil or
butter is also consumed to prevent gallstones [9]. They are
most often commenced in the outpatient setting, as efficacy is
not improved by admitting patients for the commencement of
these diets [10,11]. A period on a low-calorie diet prior to the
VLCD is not recommended. In our clinic we allow patients to
eat out at restaurants or socially (avoiding potato, rice, pasta
and bread), however one study suggested less weight loss at
12-weeks and 1-year with a ‘liberal’ (two small extra meals/
week) compared to a strict regimen [11]. Contraindications to
VLCD use are shown in Table 1. Type 1 diabetes is often listed
as an absolute contraindication to VLCD use; however, in our
experience VLCDs in selected obese patients with type 1
diabetes can be used with appropriate education and close
supervision.
Modern VLCDs are extremely safe with no increased rate of
cardiac arrhythmias [12] or electrolyte abnormalities [13,14]
seen in large trials. While early VLCDs were associated with
gallstone formation due to inadequate intake of fat, the
incidence of cholelithiasis with current day VLCDs incorpor-
ating fat is unknown. Increases in serum uric acid are often
seen[15],howeveracuteattacksofgoutarerare.Reductionsin
bone mineral density are associated with use of VLCDs [16];
however, there are no data to suggest this increases long-term
fracture risk. Side effects tend to be mild and/or transient, and
mayincludedizziness,headacheandfatigue,coldintolerance,
dry skin, temporary rash, altered bowel habit, hair loss,
muscle cramps, menstrual disturbance in women, transient
hepatic transaminase rise and halitosis (ketone breath) [17].
VLCDs are associated with ketosis via the production of
acetoacetate and beta-hydroxybutyrate from the breakdown
of circulating fatty acids. During ketogenic diets, including
VLCDs, this appears to be more dependent on the total
carbohydrate intake rather than the degree of calorie restric-
tion, although the literature is inconsistent on the level of
carbohydrate restriction required to allow ketogenesis (<50 g
of carbohydrate up to 192 g/day) [18]. Quantities of other
macronutrientsmayinfluencethis,asupto57 gofglucosecan
be produced from 100 g of dietary protein [19]. Typically, the
serum ketone levels seen are between 0.33 and 0.72 mmol/L, a
rise above a baseline level of <0.10 mmol/L, but much lower
than the levels seen in diabetic ketoacidosis, which may be up
to 25 mmol/L [18]. Some evidence exists for an appetite-
suppressive effect of ketone bodies [20,21], although there is
conflicting literature [22] and definitive evidence for a
reduction in hunger with the onset of ketosis in VLCDs
remains to be shown.
The advantages of VLCDs include rapid weight loss that
acts as a motivating factor, calorie restriction-associated
diuresis that can alleviate fluid retention, preservation of
lean body mass and probably hunger suppression by mild
ketosis. Perhaps paradoxically, the convenience of meal
Table 1 – Absolute and relative contraindications to the
use of very-low-calorie diets.
Absolute contraindicationsRelative
contraindications
BMI <25 kg/m2
Pregnancy/lactation
Clinical eating disorder
Major psychiatric illness
Severe systemic or organ disease, e.g.:
Recent myocardial infarct/angina/stroke
Major dysrhythmia
Severe renal/hepatic disease
Malignancy
Wasting disorders, such as Cushing’s
syndrome
Age >65 years
Child <16–18 years
BMI 25–30 kg/m2
Type 1 DM
Cholelithiasis
Gout
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replacements and restriction of foods improves acceptabil-
ity and adherence [17].
VLCDs produce an initial large weight loss, in the order of
1.5–2.5 kg per week, and weight losses during the intensive
phase may range from 12 to 35 kg [10]. While weight regain is
usual, there is no good evidence that regain is more rapid
comparedwithotherdietarymeansofweightreduction[10].A
2001 meta-analysis found a mean weight loss of 6.6% after
VLCD at 4.5 years (compared to 2.1% using a hypocaloric
balanced diet) [23]. Some data have suggested a gender
difference, whereby males do better on VLCDs and women
on non-VLCD programs [24]. Long-term mean weight losses
for VLCDs versus non-VLCDs show little difference [23],
however, some patients maintain significant weight loss
following VLCD programs. One study of 112 patients who
achieved >10 kg weight loss with VLCD at 12-weeks, showed
40%maintained>5%weightloss,and25%>10%at7years[25].
Behavioural therapy (keeping food diaries, employing
shopping strategies, dietary and exercise education, and so
on) is often employed in studies of VLCDs. In a study of 76
obese women, 27% maintained >5 kg weight loss at 5 years
with VLCDs plus behavioural therapy (BT) compared to 11%
withVLCDsaloneand13%withLCDsplusBT,suggestingarole
of BT in decreasing weight regain [26]. Exercise may also assist
with reducing weight regain, and we recommend low
intensity, aerobic exercise in combination with VLCD to
promote weight maintenance. In a study of 30 women,
addition of exercise to VLCD plus BT did not increase initial
weight loss but improved weight maintenance at 1 and 2 years
(?9.1 kg versus ?0.8 kg) [27]. It should be recognised that there
is a paucity of quality data looking specifically at exercise and
VLCDs combined with regard to weight loss and health
outcomes versus LCD/BT plus exercise [28].
3.VLCDs and diabetes prevention
To date, diabetes prevention programs using non-surgical or
pharmacological intervention have focused on exercise and
dietary modification and have achieved modest weight loss of
the order of 5–7% [29–31]. The Finnish Diabetes Prevention
Study used adjuvant VLCDs in 48 patients with unsatisfactory
weight loss at 6 months and showed a benefit in terms of
weight loss but no difference in diabetes incidence compared
to the non-VLCD group [30]. No randomised studies have
specifically addressed the question of diabetes prevention in
obesity or pre-diabetes using VLCDs. A consensus statement
from the International Diabetes Federation does not recom-
mend the use of VLCDs in diabetes prevention due to the lack
of evidence for benefit in achieving long-term reductions in
weight [32].
4.VLCDs as a weight loss intervention in T2D
A Cochrane review published in 2004 (amended in 2007)
concluded that insufficient quality data exist to recommend
VLCDs over other diets in T2D and called for studies to address
this question [28]. Furthermore, people with T2D may find it
harder than people without diabetes to lose weight, including
using VLCDs. A small study of 12 diabetic individuals and their
spouses undergoing behaviour modification suggested less
weight loss in the diabetic group, likely due to dietary non-
adherenceinthediabetesgroup[33].Otherstudiessupportthe
notion that individuals with T2D have greater difficulty
initiating or maintaining weight loss using dietary and
behavioural therapy [34], pharmacotherapy [7,35,36], and
bariatric surgery [37] although the literature is conflicting
[38]. Reasons often given for the decreased efficacy of weight
loss interventions in T2D include antidiabetic therapies,
especially insulin and thiazolidinediones, which promote
adipose tissue deposition and fluid retention, increased food
intake to avoid hypoglycaemia, and reduced calorie loss via
reductions in glycosuria.
With VLCDs as the intervention, a study with 15 partici-
pants showed less weight loss in the T2D VLCD group
compared to the non-diabetic VLCD group, but the T2D group
was less obese at baseline [14]. One study comparing 7 insulin
treated diabetic patients to 11 on sulfonylureas and 12 non-
diabetic controls suggested that use of insulin may impair
weight loss with VLCDs in individuals with diabetes [39].
However, conclusions were limited by the small numbers and
proportionally more women in the insulin-treated group.
Theoretically, the use of exogenous insulin or an insulin
secretagogue may reduce diet tolerability and thus efficacy
through non-adherence, as insulin directly inhibits ketogen-
esis in the liver [40]. The risk of hypoglycaemia may also
promote greater food intake, decreasing adherence. Insulin
inhibits lipolysis in adipose tissue; hence elevated levels such
as with high doses of exogenous insulin or sulfonylureas may
lead to reduced weight losses with VLCDs. However, differ-
encesin weightloss,hungerandketone levelsin patientswith
T2D on therapies that raise insulin levels have not been
demonstrated so far. Thus, firm evidence for reduced efficacy
of VLCDs in obese individuals with diabetes is lacking.
Weight regain is frequent in individuals with T2D under-
going weight loss regimens including VLCDs, as it is in non-
diabetic obese individuals. Little data exist to show a
difference in weight regain following VLCD between non-
diabetic patients and individuals with T2D. Homeostatic
mechanisms of weight regulation post-weight loss, such as
reductions in leptin [41,42], cholecystokinin [43] levels and
triiodothyronine (T3) and rises in reverse triiodothyronine
(rT3) [14] and circulating ghrelin [44] levels, are potential
modulators in weight regain through effects on satiety and
appetite and energy expenditure, both in obesity and T2D.
Studies investigating appetite suppression via pharmacother-
apy in obese and T2D individuals in the post-VLCD period are
ongoing.
Practical considerations in people with diabetes under-
going VLCDs include the risk of hypoglycaemia with sulfony-
lureas and insulin, and doses are generally halved at
commencement of VLCDs. Further adjustment and close
glycaemia monitoring is mandatory. Antihypertensives and
diuretic therapies often need adjustment to prevent hypoten-
sion and dehydration. The co-existence of renal impairment
should also be considered. While end-stage renal failure is an
absolute contraindication, lesser degrees of chronic renal
impairment may benefit. No deterioration in renal function
was seen in one study including 11 patients with T2D and
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serum creatinine >130 mmol/L [45], while another study
showed increased creatinine clearance and reduced protei-
nuria in 24 patients with T2D undergoing a VLCD [46]. Prior to
commencement of a VLCD in the diabetic patient screening
investigations therefore should include markers of glycaemic
control such as glycosylated haemoglobin A1c (HbA1c), serum
electrolytes and renal function, liver function tests, thyroid
function, lipid profile and uric acid level, urinary albumin, and
an electrocardiogram (ECG).
5.VLCDs effect on glycaemia in T2D
Effects of VLCDs on plasma glucose levels occur rapidly, with
falls in mean glucose levels seen within days and reaching
near-nadir after 1–2 weeks [47]. The majority of the glucose-
lowering effect seems related to calorie restriction, whereas
weight loss has an increasing contribution with time via
reductions in intraabdominal (visceral) adipose tissue [48–50].
In a 12-week study of 14 obese patients with T2DM using
VLCDs, marked improvement was seen in glycosylated HbA1c
[51]. Twelve-month follow-up data in nine individuals showed
a rise in HbA1c but this remained below baseline (8.8% versus
8.1%, p < 0.05) [52]. Another study in 36 obese subjects with
T2D compared the addition of a VLCD or LCD to a 20-week
behavioural program [53]. At 20 weeks significantly more
weight was lost in the VLCD group (18.6 kg versus 10.1 kg),
however this was not sustained over the next 12 months
(8.6 kg versus 6.8 kg). Significant differences were maintained,
however, with respect to fasting glucose levels (9.17 mmol/L
versus 11.78 mmol/L) and HbA1c while antidiabetic medica-
tion use at 72 weeks was similar between groups. However, a
subsequent study looking at intermittent use of VLCD in 93
people with T2DM led to only modestly better weight loss at 1
year (14.2 kg versus 10.5 kg) and no improvement in HbA1c,
glucose or insulin levels compared to yearlong LCD [54]. A 5-
year study of 15 obese patients with T2D (two with recent
onset) showed no significant differences by study’s end in
fructosamine or fasting glucose levels, although one patient
sustained >10 kg weight loss and remained in remission from
diabetes at 5 years [55].
Beta-cell function in people with T2D undergoing VLCD
treatment improves but remains significantly impaired [56].
Both people without diabetes and people with T2D show a fall
in fasting plasma insulin/c-peptide levels [57]. In T2D patients
no return of the first-phase insulin response is seen. However,
there are improvements in dynamic insulin secretion and
overall insulin production, modulation of pulsatility and
improved synchrony [58]. High-ketogenic VLCDs lower glu-
cose more than low-ketogenic VLCDs in obese T2D patients,
possibly by reducing hepatic glucose output [59]. It has been
demonstrated that ketone bodies can stimulate insulin
secretion in normal humans [60] but it is unlikely that this
has a significant clinical effect in people with diabetes on
ketogenic diets, firstly as levels are relatively low and secondly
there is evidence of reduced effects in diabetes [61]. Ketones
can, however, directly suppress the elevated hepatic glucose
output in T2D [59]. It has been hypothesised that mild ketosis
may improve peripheral insulin resistance, as studies on
cardiac muscle have shown that – within limits – ketones can
mimic the acute effects of insulin on the myocardium,
including increasing intracellular glucose concentrations,
mitochondrial energy production and the efficiency of the
working heart [62]. Other investigators suggest a reduction in
Fig. 1 – Schema for the effects of VLCDs on glycaemia. Calorie restriction leads to glycogen depletion in muscle and liver.
Restriction of carbohydrate (CHO) leads to lipolysis and the formation of ketone bodies by the liver [18]. Together, these lead
to reductions in hepatic glucose output via inhibition of gluconeogenesis and reduced glycogenolysis [59,61,62]. High
protein stimulates insulin secretion [64] and increases satiety [65]. Circulating ketone bodies probably contribute to
tolerability of the diet by suppressing appetite in the hypothalamus [20]. Weight loss and diminution of fat depots in the
liver, muscle and peri-visceral space lead to reductions in insulin resistance [49,50]. Improved insulin sensitivity, dynamic
insulin secretion and reduced hepatic glucose output lead to reductions in blood glucose levels [57,58].
diabetes research and clinical practice xxx (2009) xxx–xxx
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cardiac insulin sensitivity with chronic ketone body exposure
[63]. The effects of VLCDs on glycaemia are summarised in
Fig. 1.
6. VLCDs on cardiovascular risk factors in T2D
VLCDs produce multiple beneficial effects on metabolic
parameters in patients with T2D by virtue of both calorie
restriction and weight loss. Generally, blood pressure (systolic
and diastolic) falls. Orthostatic hypotension can occur early
due mainly to dehydration caused by glycogen depletion-
related diuresis and sodium losses [56]. Triglycerides fall by
around 25%, and total cholesterol and LDL-C generally also are
reduced [56]. HDL-C results are variable, and seem dependent
on the degree of weight loss and the time frame. Typically,
there is little change in HDL-C levels during the VLCD period,
with a subsequent rise with sustained weight loss [66].
Weight loss in obesity and diabetes has been shown to
improve left ventricular systolic and diastolic function and
reduce left ventricular mass [67,68]. Short-term (under 1
week) VLCD was shown to be associated with increased
intracardiomyocellular triglyceride and decreased left ven-
triculardiastolic function in healthy and T2D patients [69,70],
however over the intermediate term this resolved and net
improvements in myocardial function in diabetic patients
were seen [71].
In non-alcoholic fatty liver and steatohepatitis, VLCDs
produce a reduction in liver size and fat volume within 6 weeks
[72]. Transient rises in liver enzymes – possibly due to rapid
mobilisation of intracellular triglycerides and fatty acid release
causingportalinflammation–arereversedwithweightloss[73]
and fall below baseline with weight maintenance [10].
Thepatientpopulationwithdiabeteshasathreefoldhigher
prevalence of obstructive sleep apnoea [74]. VLCDs have been
shown to significantly improve sleep apnoea even with only
very modest weight loss, and favourable effects on baroreflex
sensitivity may have prognostic implications [75].
7.
VLCDs in T2D
Current recommendations for the use of
No body currently recommends VLCDs for use in T2D or in
obesepatientsathighriskofdiabetesfordiabetesprevention,
citing the lack of evidence for better long term weight loss
compared with other non-surgical interventions [4,28,32].
The long-term effects of VLCDs on glycaemic control,
cardiovascular risk and diabetic complications are generally
small or absent, and there are no data on the long-term effect
on complications and mortality. Therefore, in whom should
VLCDs be used? Outside of the fairly well-established pre-
bariatric surgery indication, consideration could be given to
individual patients with multiple obesity-related comorbid-
ities requiring burdensome polypharmacy, patients with
obesity-related end-organ dysfunction such as renal hyper-
filtration or cardiac diastolic dysfunction, or those with
difficult to control diabetes despite multiple oral agents
(perhaps as an alternative to commencement of insulin
therapy) or very high doses of exogenous insulin. VLCDs
should be utilised as part of an effort to institute lifestyle
change, especially commencement of an exercise pro-
gramme, and with dietary education reviewing standard
tenets of the diabetes diet and also focussing on food choice
and behavioural modification. In our experience, particularly
in obese patients with diabetes and comorbidities inhibiting
lifestyle interventions (such as sleep apnoea and osteoar-
thritis), the rapid weight loss achieved with VLCDs can be
both a catalyst to implement necessary lifestyle changes and
can also facilitate the implementation of such changes by
improving well-being, energy levels and factors such as sleep
quality, symptomatic hyperglycaemia and joint pain. While
theliteratureshowsthatthelong-termeffectonweightlossis
generally disappointing, individual cases show significant
beneficial effects from this approach [76].
8.Further research in VLCDs and T2D
Further long-term randomised trials in obesity looking at
weight loss durability with VLCDs versus other interventions
are warranted. However, it is likely that most research will
focus on novel weight maintenance strategies, especially
pharmacological, post-VLCDs. The efficacy of VLCDs in T2D
versus the non-diabetic obese remains to be clearly eluci-
dated, in particular the effect of exogenous insulin therapy or
insulin secretagogues on weight loss with VLCDs in T2D.
Specific areas for further research include use of VLCDs for
diabetes prevention in high-risk populations, such as
individuals with impaired glucose tolerance or women with
polycysticovariansyndrome.Inaddition,acomparisonofthe
efficacy of VLCDs in newly diagnosed T2D versus conven-
tional lifestyle intervention or bariatric surgery should be
performed. The current absence of data on long-term
glycaemic control and micro- and macro-vascular complica-
tions following VLCD use in T2D highlights the need for
quality trials in this area.
Conflict of interest
Joseph Proietto is Chair of the Optifast Medical Advisory
Committee for Nestle Nutrition and serves on the Medical
Advisory Board for Abbott Pharmaceuticals.
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Diab. Res. Clin. Pract. (2009), doi:10.1016/j.diabres.2009.06.002

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diabetes research and clinical practice xxx (2009) xxx–xxx
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DIAB-4541; No of Pages 8
Please cite this article in press as: S. Baker, et al., Effects and clinical potential of very-low-calorie diets (VLCDs) in type 2 diabetes,
Diab. Res. Clin. Pract. (2009), doi:10.1016/j.diabres.2009.06.002

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diabetes research and clinical practice xxx (2009) xxx–xxx
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DIAB-4541; No of Pages 8
Please cite this article in press as: S. Baker, et al., Effects and clinical potential of very-low-calorie diets (VLCDs) in type 2 diabetes,
Diab. Res. Clin. Pract. (2009), doi:10.1016/j.diabres.2009.06.002