Plasma Somatostatin-like Immunoreactivity Responses to a Mixed Meal and the Heterogeneity in Healthy and Non-Insulin-Dependent (NIDDM) Diabetics

Abstract

Peripheral plasma somatostatin-like immunoreactivity (SLI) was estimated in non-extracted plasma using a specific somatostatin-14 (SS-14) antiserum. The basal plasma SLI level in healthy subjects (n=18) was 43±2.9pg/ml (mean±SE) and rose significantly to 8.3±2.7, 7.3±1.1 and 5.8±2.1pg/ml above the mean basal level 20, 30, and 40min after a mixed meal, respectively (P<0.05). Basal plasma SLI levels in diet (n=8), sulfonyl urea (n=8), and insulin groups (n=8) of non-insulin-dependent maturity onset diabetics (NIDDM) were 50±1.6, 59±4.5, and 74±5.8pg/ml, respectively. The basal levels for patients with NIDDM were significantly higher than those for healthy subjects (P<0.05). No significant increases in plasma SLI were observed after a mixed meal in any group of NIDDM subjects. Elevated plasma SLI levels are considered to be closely related to the severity of the diabetes. The ratios of SS-14 and SS-28 to the total amount of basal plasma SLI were analyzed using high pressure liquid chromatography (HPLC). The ratio of SS-14 to the total SLI was 71-80% in healthy subjects. The ratio of SS-28 to the total SLI increased from 26-30% in the diet group to 50-55% in the group on insulin. These findings suggest a possible pathophysiological role for gastrointestinal somatostatin in NIDDM.