Pharmacological and lifestyle interventions to prevent or delay type 2 diabetes in people with impaired glucose tolerance: systematic review and meta-analysis
BMJ 2007; 334 doi: https://doi.org/10.1136/bmj.39063.689375.55 (Published 08 February 2007) Cite this as: BMJ 2007;334:299
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Thank you for your interest in our paper and for raising some
interesting issues. Of the trials studying lifestyle interventions in our
meta-analyses the majority focused on overweight individuals, with only
the DPP and DPS trials having a mean study BMI within the obese range. No
single study restricted participants to only those in the overweight
range. To assess the effect of interventions in the overweight, individual
patient data, or data stratified by BMI category would be needed, and this
was not available to us.
Competing interests:
Kamlesh Khunti has received sponsorship for attending conferences and small honoraria from pharmaceutical companies that manufacture hypoglycaemic and anti-obesity drugs.
Competing interests: No competing interests
We would like to thank Ingrid Mühlhauser for her comments. Ideally
all the important outcomes would have been considered in our meta-analyses
of diabetes prevention studies, unfortunately we were restricted by the
outcomes reported. As you point out in your paper(1) the DPP study did not
report results of HbA1c in their main publication, and neither blood
glucose nor HbA1c values were reported as outcomes in the core
publications of the STOP-NIDDM study, the smaller studies used in our meta
-analyses were further limited in their reported results.
It is true that taking a continuous variable and categorising it into
IGT and diabetes using arbitrary cut-offs is oversimplifying the problem,
especially when risk of complications increase with increasing blood
glucose and HBA1c levels. But the important issue for patients is whether
they have the disease or not. As only those classified as having diabetes
will receive treatment, it could be argued that presence or absence of
diabetes is the most important clinical outcome to report.
We agree that it is important to report results in a manner that
enables clinicians to make an accurate interpretation of the intervention
effect. To this end we reported our results not just as relative risks
but, as suggested in your paper (1), also in the form of absolute risk
reduction and numbers needed to treat.
1) Mühlhauser I, Kasper J, Meyer G, FEND. Understanding of diabetes
prevention studies: questionnaire survey of professionals in diabetes
care.
Competing interests:
Kamlesh Khunti has received sponsorship for attending conferences and small honoraria from pharmaceutical companies that manufacture hypoglycaemic and anti-obesity drugs.
Competing interests: No competing interests
Lifestyle Changes and/or Drugs for overweight patients without
obesity ?
Sir,
Successful maintenance of the lifestyle changes needed for optimum
bodyweight is usually considered to be uncommon and the current methods
for lifestyle modifications (alone) as treatment for obesity are widely
regarded as ineffective(1).Meta-analysis by Gillies et al in BMJ challenge
this point (2) Absence of durable efficacy of lifestyle modifications is
generally observed using data collected in obese patients with BMI
≥30 Kg/m2.The results could be different in individuals with
overweight and BMI between 25 ans 30 kg/ m2.. Comparison with alcohol is
interesting : for alcohol ,withdrawal or return to moderate consumption
is clearly more effective in excessive alcohol consumption without
dependency(efficacy of brief intervention) than in case of alcoholism
.Public health impact of general practitioner using brief intervention is
considerable as the number of alcohol at risk population is more
important than alcohol dependant population (3,4).In a similar way ,
this aspect could be of major importance in nutritional problem with
overweight and obese patients: the number of overweight patients in the
world exceed for three-four times the number of obese patients ; however
the pessimistic view of physicians for lifestyle modifications duration
effect in case of overweight has as a consequence too frequent
systematic prescription of drugs. It would be problematic to prescribe a
drug in all the world for all the overweight individuals, even if the
promising new drugs (5) were largely available .
So, the question for Gillies et al is : are data available focusing
not only on obese patients but also in overweight patients without
obesity, looking at the durability of the weight loss under lifestyle
prescription only?
it could be suspected that durability of the weight loss induced by
lifestyle changes would be longer in patients with overweight and BMI less
than 30 Kg/m2(6),potentially less “dependent” of nutritional intake . If
so , a more positive aspect of lifestyle prescriptions could be proposed
in the so call metabolic syndrom in prevention of diabetes but also for
the other complications ( cardiovascular ,hepatic..) of this syndrom.
Consequences in term of public health would be of major importance .
(1) National Heart ,Lung and Blood institute Obesity Education
initiative.Clinical guidelines on the identification ,evaluation and
treatment of overweight and obesity in adults .the evidence report
.Bethesda,MD:US department of Health and Human services .1998
(2 ) Gillies CL, AbramsKR, Lambert PC,Cooper NJ,Sutton AJ,Hsu
RT,Khunti K
Pharmacological and lifestyle interventions to prevent or delay type 2
diabetes in people with impaired glucose tolerance : systematic review and
meta-analysis
BMJ 2007 jan 19 on line
(3) Miller WR, Rollnick S : Motivational interviewing : preparing people
to change addictive behavior . New York : Guilfort Press, 1991
(4) O’Connor PG, Schottenfeld RS : patients with alcohol problems. N
Engl J. Med 1998 ; 338 : 592-602
(5) Padwal RS , Majumdar SR .Drug treatments for obesity:orlistat
,sibutramine and rimonabant The Lancet 2007;369:71-77
(6) Wing R,Tate D ,Gorin AA, Raynor HA,Fava JL .A self-regulation
Program for maintenance of weigth loss .N Engl J Med 2006;355:1563-71
Patrice Couzigou
Pr Patrice COUZIGOU
Service d’HépatoGastro-Entérologie
Hôpital du Haut-Lévèque Pessac
Bordeaux University France
patrice.couzigou@chu-bordeaux.fr
Competing interests:
None declared
Competing interests: No competing interests
In their systematic review of diabetes prevention studies the authors
have reported only data on diabetes risk. We have shown that this is
misleading and results in substantial overestimation of the clinical
relevance of the effects of interventions for diabetes prevention (1). The
authors should also report the data on the underlying changes of glucose
and HbA1c values.
Health professionals rate diabetes prevention studies as being important
much more frequently when results are shown as changes in diagnostic
categories rather than as changes in the continuously distributed measure
of glucose (1). In our survey of diabetologists and diabetes educators
effects were interpreted as important or very important by 92% (255 of 276
survey participants) when results were presented as proportions of
subjects with diabetes (14% intervention group, 29% control group), by 87%
(248/285) when communicated as a risk reduction of 57%, but by only 39%
(110/284) when the corresponding fasting plasma glucose values were
presented (mean difference 0.3 mmol/L), and by only 18% (52/283) when
glycosylated haemoglobin values were used (6.0% versus 6.1%). These
results show that health care professionals view the benefit of preventive
interventions substantially higher when changes in diabetes risk are
communicated rather than related glycaemic parameters. Transformation of
continuous metabolic data into diagnostic categories may interfere with
understanding of study effects. This aspect has also been addressed in a
recent editorial in Lancet (2).
1) Mühlhauser I, Kasper J, Meyer G, FEND. Understanding of diabetes
prevention studies: questionnaire survey of professionals in diabetes
care. Diabetologia 2006; 49:1742-1746
2)Tuomilehto J, Wareham N. Glucose lowering and diabetes prevention:
are they the same? The Lancet 2006;368:1218-1219.
Competing interests:
None declared
Competing interests: No competing interests
Re: Re: Glucose values should be reported
I do not agree with the authors' response. The important outcome
measure for diabetes prevention intervention studies should not be a more
or less arbitrarily defined and obviously misleading diagnostic category
(1). It is worrying that the metabolic parameters (glucose and HbA1c
values) that are the basis for the diagnostic categories (diabetes yes/no)
and which have been defined as outcome parameters in study protocols are
not reported in all studies or difficult to extract from the publications
(1). Also, in the recently published follow-up of the Finnish Diabetes
Prevention Study neither glucose values nor HbA1c values are reported
(2). It may be speculated that this information is withheld because of
only marginal changes without clinical relevance. What really would matter
to persons who undergo diabetes prevention interventions is the effect on
clinically relevant outcome measures such as microvascular or
cardiovascular complications. There is no evidence to support an important
effect of such minimal changes of blood glucose values on microvascular
complications, and, there is still lack of evidence of relevant effects on
cardiovascular disease. The question remains whether it is justified to
label persons as "diabetic" just because of minimal changes in blood
glucose values which are insufficiently understood even by diabetes health
care providers (1). In any case the authors should include the available
information on glucose values in their review. Otherwise, this review will
further promote misconceptions about efficacy of diabetes prevention
intervention studies.
1) Mühlhauser I, Kasper J, Meyer G, FEND. Understanding of diabetes
prevention studies: questionnaire survey of professionals in diabetes
care. Diabetologia 2006; 49:1742-1746
2) Lindström J et al. Sustained reduction in the incidence of type 2
diabetes by lifestyle intervention: follow-up of the Finnish Diabetes
Prevention Study. Lancet 2006; 368: 1673-1679
Competing interests:
None declared
Competing interests: No competing interests