![]()
REVIEW
SA JOURNAL OF DIABETES & VASCULAR DISEASE
68
VOLUME 8 NUMBER 2 • JUNE 2011
Weight loss with diet and exercise regimens has been shown to
effectively improve glycaemic control.
22,23
Data from a systematic
review of weight-loss studies in type 2 diabetes patients indicate
that an average weight loss of 9 kg can be expected following
dietary interventions, as well as a 2.7% reduction in HbA
1C
.
23
A
more recent meta-analysis of randomised controlled trials with
a minimum follow-up period of 12 months demonstrated that
lifestyle interventions can result in a modest pooled weight loss
of 1.7 kg (3.1% of initial body weight) in type 2 diabetes adults,
with improvements in HbA
1C
of up to 2.6%.
4
Of note, most of the
trials studying dietary interventions for type 2 diabetes are short
term and data regarding long-term efficacy are insufficient to
establish definitive conclusions for clinical practice.
4
The ongoing
Look AHEAD trial is investigating the long-term effect of intensive
lifestyle changes on cardiovascular mortality and morbidity in
overweight and obese patients with type 2 diabetes.
24
Early results
have shown that intensive lifestyle changes in these patients result
in significant weight loss of 8.6% of their initial weight after
one year, with concomitant improvements in glycaemic control.
25
However, lifestyle changes alone usually offer limited long-term
glycaemic control.
22
Indeed, the UKPDS has demonstrated that the
proportion of patients who maintain glycaemic targets with diet
alone drastically declines over time: 23% of overweight patients
with type 2 diabetes maintained HbA
1C
<
7.0% after three years
of treatment with diet alone compared to 11% after nine years.
26
Hence, most patients with type 2 diabetes will require additional
treatments to achieve glycaemic goals in the longer term.
22
Pharmacotherapy
Pharmacotherapy for weight loss in obese patients with type 2
diabetes should be considered early in the management plan as an
addition to lifestyle interventions (Table 1).
18–20
Orlistat is a gastric and pancreatic lipase inhibitor that decreases
fat digestion and thereby reduces the availability of dietary
triglycerides for absorption. At present, it remains the only available
licensed anti-obesity drug in the UK for long-term use.
27
Sibutramine
is a centrally acting monoamine-reuptake inhibitor which enhances
satiety and the feeling of fullness. This has recently been suspended
by the EMA after a review of available data which demonstrated
that the weight benefits do not outweigh the cardiovascular risks
associated with its use.
28
Initiation of treatment with orlistat is
generally recommended in type 2 diabetes patients with a BMI
>
28 kg/m
2
.
18
After an initial three-month period, its efficacy should
be evaluated and subsequently the treatment should be continued
only if satisfactory weight loss is achieved. A reduction of
>
5% of
the initial body weight is typically regarded as adequate, but in the
presence of type 2 diabetes less strict goals are accepted (e.g.
>
3%
weight loss).
18,20
The key features of orlistat have been summarised
in Table 2.
Orlistat has been evaluated for the management of overweight
and obese patients with type 2 diabetes. In a recent review
of clinical trials in type 2 diabetes patients, it was reported that
orlistat treatment over one year reduces weight by 3.9–6.2 kg,
compared with 1.3–4.3 kg with placebo, and leads to significant
improvements in HbA
1C
levels (0.28–1.1%).
12
Of note, the efficacy
of orlistat is significantly limited by poor long-term treatment
compliance. Indeed, data from a retrospective study in Canada
demonstrated that adherence to orlistat treatment was less than
10% after one year and 2% after two years.
29
Clearly, new, safe
and more effective anti-obesity medications that also encourage
patients’ compliance are warranted.
Bariatric surgery
Bariatric surgery should be considered as the final step in the
weight-management strategy, also in combination with appropriate
lifestyle modification (Table 1).
18–20
Recent guidelines recognise the
benefits of bariatric procedures in carefully selected type 2 diabetes
patients with BMI
≥
35 kg/m
2
and inadequate glycaemic control.
30
Furthermore, surgical weight-loss interventions can be considered
as an alternative treatment for poorly controlled type 2 diabetes
Table 1.
A guide for deciding the initial level of intervention to discuss with patients based on BMI, waist circumference and presence of comorbidities
18,20
WHO classification* [BMI]
Waist circumference*
Comorbidities present
†
Low
[men
<
94 cm; women
<
80 cm]
High
[men
≥
94 cm; women
≥
80 cm]
Overweight
[BMI: 25–29.9 kg/m
2
]
0
12
Obesity class I
[BMI: 30–34.9 kg/m
2
]
1
2
2
Obesity class II
[BMI: 35–39.9 kg/m
2
]
2
‡
2
3
Obesity class III
[BMI:
≥
40 kg/m
2
]
3
‡
3
3
0: General advice on healthy weight and lifestyle
1: Lifestyle intervention; diet and physical activity for weight loss
2: Lifestyle intervention; consider pharmacotherapy for weight loss
3: Lifestyle intervention; consider pharmacotherapy for weight loss; consider bariatric surgery
*BMI and waist circumference cut-off points differ in certain ethnic groups (e.g. Japanese and South Asians).
†
Comorbidities such as T2DM, hypertension, dyslipidaemia, cardiovascular disease, osteoarthritis and sleep apnoea.
‡
The combination of BMI
≥
35 kg/m
2
with low waist circumference is practically not applicable.
BMI
=
body mass index; T2DM
=
type 2 diabetes mellitus; WHO
=
World Health Organisation.
