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

2-h plasma glucose levels during an OGTT are better predictors
of cardiometabolic disease than fasting glucose levels

The link between the capacity to regulate blood glucose level after an OGTT and the risk of cardiovascular
disease has been studied in a very large cohort of non-diseased subjects by Ning and colleagues. Data from
19 European cohorts including 12,566 men and 10,874 women were included. All of the subjects participated
in an OGTT and had a fasting glycemia below 6.1 mmol/l and a glycemia at 120 min below 7.8 mmol/l.
This large sample was divided in two groups based on the subjects’ glycemic values at 120 min after ingestion
of a 75 g glucose solution. In group I, subjects’ 2-h plasma glucose levels were either equal to or lower than
their fasting levels, whereas in group II, the 2-h plasma glucose levels were greater than fasting levels.
A higher rate of mortality linked to cardiovascular disease was observed in group II during follow-up (median
of nine years), and subjects in group II had a higher rate of all-cause mortality (18%) compared to group I
[Ning et al., 2010].
Thus, both studies [Abdul-Ghani et al., 2006b; Ning et al., 2010] showed that in subjects with normal glucose
tolerance, an elevated 2-h plasma glucose level after ingestion of a 75 g glucose load is predictive of type 2
diabetes, cardiovascular diseases, and all-cause mortality.

The potential underlying mechanisms involving postprandial hyperglycemia
and cardiometabolic risks

Several mechanisms related to postprandial hyperglycemia may be involved in the cardiovascular risks.
Three complementary areas of evidence (epidemiology, pathophysiology, and randomized intervention
studies) have been used to study the specific impact of postprandial hyperglycemia and glycemic variability
on vascular complications [Standl et al., 2011]. Postprandial hyperglycemia induces a higher level of
oxidative stress both in healthy subjects and in patients with type 2 diabetes. Oxidative stress is related to
endothelial function disorder, primarily due to a decrease in the release of nitric oxide. This phenomenon
may be exacerbated by an increase in the levels of specific circulating inflammatory cytokines. In addition,
several markers of cardiovascular risk have been observed under hyperglycemic conditions, including an
increase in blood coagulation, a reduction in fibrinolysis, and a decrease in plaque stability. Furthermore, the
lipemic profile deteriorates, with a reduction in triglyceride-rich lipoproteins and LDL-cholesterol removal,
an increase in HDL-cholesterol catabolism, and a decrease in free fatty acids. The last factor involved in this
deleterious cascade of events is insulin dysregulation with a reduction of the early phase secretion and an
increase in insulin resistance.

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