Abstract
The interaction of nutrients with the small intestine modulates postprandial cardiovascular function. Rapid small intestinal nutrient delivery may reduce blood pressure markedly, particularly in patients with type 2 diabetes (T2DM). Postprandial hypotension occurs in ~30% of patients with longstanding T2DM, but there is little information about the cardiovascular effects of different macronutrients. We compared the blood pressure and heart rate responses to standardized intraduodenal glucose and fat infusions in T2DM. Two parallel groups, including 26 T2DM patients who received intraduodenal glucose infusion and 14 T2DM patients who received intraduodenal fat, both at 2 kcal/min over 120 min, were compared retrospectively. Blood pressure and heart rate were measured at regular intervals. Systolic blood pressure was stable initially and increased slightly thereafter in both groups, without any difference between them. Diastolic blood pressure decreased in response to intraduodenal glucose, but remained unchanged in response to lipid, with a significant difference between the two infusions (P = 0.04). Heart rate increased during both intraduodenal glucose and lipid infusions (P < 0.001 each), and the increment was greater in response to intraduodenal fat than glucose (P = 0.004). In patients with T2DM, intraduodenal fat induced a greater increase in heart rate, associated with a diminished reduction in blood pressure, when compared with isocaloric glucose. The macronutrient composition of meals may be an important consideration in T2DM patients with symptomatic postprandial hypotension.
Highlights
Exposure of the small intestine to ingested nutrients is associated with a substantial increase in splanchnic blood flow and a decrease in peripheral blood volume, which may lead to a reduction in blood pressure and, in some cases, postprandial hypotension [1]
Diastolic blood pressure decreased by ∼5 mmHg within the first 60 min followed by a slow recovery during glucose infusion, but remained unchanged during lipid infusion, such that the reduction in diastolic blood pressure was greater in response to intraduodenal glucose than lipid (Figure 1B)
In patients with relatively well-controlled, uncomplicated T2DM, we observed a reduction in diastolic blood pressure in response to intraduodenal glucose infusion at a rate of 2 kcal/min, but not to an isocaloric fat infusion, probably due to its greater effect to increase heart rate
Summary
Exposure of the small intestine to ingested nutrients is associated with a substantial increase in splanchnic blood flow and a decrease in peripheral blood volume, which may lead to a reduction in blood pressure and, in some cases, postprandial hypotension (a fall in systolic blood pressure of ≥20 mmHg within 2 h of a meal) [1]. The latter occurs frequently in patients with type 2 diabetes (T2DM), and predisposes to syncope, fall and stroke [1]. The comparative effects of different nutrients on blood pressure and heart rate have not been investigated in patients with T2DM
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