Diabetes Care note that the studies
cited by these organizations frequently had small numbers of
participants, focused on people
who did not have diabetes, and
generally provided only average
weight and heart risk factor
reductions. The current study
focuses solely on people with
Type 2 diabetes and attempts to
correlate the magnitude of
weight reduction with the lowering of risk factors.
The study is an analysis of participants in a multicenter, randomized clinical trial called Look
AHEAD (Action for Health in
Diabetes). The long-term trial,
which is still under way, is examining the effects of lifestyle interventions on cardiovascular
disease and death in 5,145 overweight or obese people with Type
2 diabetes. About 40% of the participants are men and 60%
women, they range in age from
45 to 75, and a little more than a
third of them represent racial
and ethnic minorities. The current study examines the association between the amount of
weight lost and the size of the
improvements in blood glucose
control, blood pressure, and cholesterol levels after one year.
Participants in Look AHEAD
were randomly assigned to either
intensive lifestyle intervention
(ILI) or “usual care,” generally
called Diabetes Support and Education (DSE). The ILI group had
a target of losing 10% of their
body weight through diet and
exercise. They were seen weekly
for six months then three times
each month for the next six
months, with a heavy program of
education and support. They
were assigned a daily calorie
intake of 1,200– 1,800 calories
depending on their initial weight.
No more than 30% of the calories were to be from fat, and
meal-replacement products were
used. Their physical activity was
increased to a targeted 175 minutes each week of moderate
exercise.
The DSE group did not have a
specified weight-loss goal and
attended three meetings during
the course of the year with a
focus on diet, activity, and social
support.
Over the year, 67% of the ILI
group lost weight, compared with
49% of the DSE group. A full
25% of the DSE group remained
stable, while only 11% of the ILI
group remained stable.
To help determine the correlation between weight loss and
changes in risk factors over the
one-year period, the participants
were divided into six groups:
those who gained more than 2%
of their weight, those who stayed
the same, and those who lost 2%
to 5%, 5% to 10%, 10% to 15%,
and more than 15%.
Weight loss had a significant
association with positive changes
in blood glucose control (
measured by fasting glucose and
HbA1c, a measure of control over
time), blood pressure, HDL cholesterol, and triglycerides. The
greater the weight loss, the
greater the improvements. Even
though the DSE group lost less
weight overall, lowered weight
was still associated with improvements, and the improvements
were positively related to the
amount of the weight loss. Interestingly, weight loss was not associated with improvement in LDL
cholesterol levels in either group.
Specifically, those participants
who lost 5% to 10% of their ini-
tial body weight had a 0.5-point
reduction in HbA1c, a 5-point
decrease in both diastolic and sys-
tolic blood pressure, a 5-point
increase in HDL cholesterol, and
a 40-point drop in triglycerides.
This column is written by Wayne
Clark, a freelance medical and science
writer who has written extensively on
diabetes. He lives in Oregon.
