[Postprandial hypotension and gastric emptying in longstanding diabetes mellitus]

Postprandial hypotension is commonly defined as a decrease in systolic blood pressure of 20 mmHg and more within 2 hours after meal ingestion. It was described in autonomic nervous system failure of different origin, among others in diabetes mellitus. Pathomechanism of postprandial hypotension is not entirely understood. The rol of gastric emptying disorders is considered as an important factor. The aim of the study was to evaluate the concordance between gastric emptying and postprandial blood pressure changes in diabetic patients. The study involved 67 subjects (26 males, 41 females, mean age: 47.5 +/- 16.2 years) diagnosed either with diabetes mellitus type 1 or 2 (disease duration: 13.3 +/- 8.8 years) and treated with diet and insulin injections. Postprandial hypotension was recognised based on results of automatic blood pressure recordings within 90 minutes after test meal ingestion, according to the criterion mentioned above. Gastric emptying was assessed scintigraphically. The parameters evaluated were: gastric half emptying time (T1/2 max) and residual activity registered over stomach area at 45 minute of the study. Both blood pressure monitoring and gastric emptying were assessed concurrently. In investigated patients mean fall in systolic blood pressure of 17.7 +/- 11.7 mm Hg was recorded at 48.0 +/- 13.7 min of the study. Based on systolic blood pressure monitoring results patients were divided into two groups: group A of 39 patients (58.2%) without postprandial hypotension, and group B of 28 patients (41.8%) with pathological reaction of systolic blood pressure to meal. The average decrease in systolic blood pressure was 8.9 +/- 4.4 mm Hg in group A and 30.0 +/- 6.2 mmHg in group B, the difference was statistically significant (p < 0.001). Gastric emptying parameters in both groups did not differ significantly (T1/2 max: group A 68.4 +/- 31.1; group B 70.8 +/- 39.1 min, p = 0.96; residual activity over stomach area at 45 min of the study: 64.5 +/- 18.6% and 62.6 +/- 24.3% accordingly, p = 0.80). No statistically significant correlation between gastric emptying half time (T1/2 max) and magnitude of postprandial systolic blood pressure fall was noted (Spearman's correlation co-efficient R: -0.041, p = 0.74). Statistically significant correlation was found between T1/2 max value and time in which systolic blood pressure reached its nadir (Spearman's correlation co-efficient: 0.527, p < 0.0001).

Gastric emptying was not recognised as an important factor influencing the magnitude of postprandial hypotension in diabetic patients, however it may significantly change the dynamics of postprandial blood pressure decrease.