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NutrInsight • Slow-release carbohydrates: Growing evidence on metabolic responses and public health interest

3.4 Diet and lifestyle interventions can reduce the risk
of metabolic diseases

Very few long-term intervention studies have directly addressed the interest of decreasing the postprandial
glycemic response for preventing metabolic diseases (diabetes or cardiovascular events). One very large
cohort of 1,368 subjects with impaired glucose tolerance from nine countries was followed for 3 to 4 years
[Chiasson et al., 2002; Chiasson et al., 2003]. The decrease in postprandial hyperglycemia was achieved
by adding acarbose to each meal. Acarbose is an alpha-glucosidase inhibitor. Because of the decrease in
postprandial hyperglycemia, the subjects in this study experienced an increased reversion in metabolic
status from impaired to normal glucose tolerance. OGTTs were used to determine the change in glycemic
control. In addition, there was a decreased cumulative incidence of type 2 diabetes when the postprandial
hyperglycemia was limited (32%) compared to the control group (42%) [Chiasson et al., 2002]. Cardiovascular
events were also measured in the same cohort [Chiasson et al., 2003]. Limiting postprandial hyperglycemia
was associated with a 49% reduction in the relative risk of developing cardiovascular events (2.5% absolute
risk reduction). The two major reductions were in the risk of myocardial infarction and hypertension. Thus,
the better control of postprandial hyperglycemia by consuming acarbose was able to either revert the
impaired metabolic status of the study subjects and to decrease the risk of developing type 2 diabetes and
experiencing cardiovascular events.

A complementary approach including the control of postprandial glycemic response is modifying the
overall lifestyle. This approach includes strict control of the diet according to nutritional guidelines and the
introduction of regular physical activity. A study on lifestyle intervention called the SLIM (Study on Lifestyle
intervention and Impaired glucose tolerance Maastricht) study was conducted in a group of 147 subjects
with impaired glucose tolerance, and included three years of follow-up [Roumen et al., 2008]. Lifestyle
changes, consisting of a dietary element and a physical activity element, were prescribed for each subject
in the intervention group. The dietary recommendations were based on the Dutch guidelines for a healthy
diet (Dutch Nutrition Council), and subjects also received advice on how to increase their level of physical
activity to at least 30 min a day for at least 5 days a week. The results showed that subjects with a healthier
lifestyle improved their glycemic control, which was evaluated by
OGTT four times during the three years of follow-up (see
Figure 17). At the end of intervention, there was an
approximately 1 mmol/l difference in the postprandial
glycemic response at the 120 min time point of the
OGTT. Even though this value may not seem very
large, it was related to a significant reduction
by 50% in the cumulative incidence of type 2
diabetes over the entire three year period.
Surprisingly, fasting plasma glucose levels
did not improve.

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