Upper gastrointestinal function and glycemic control in diabetes mellitus

Abstract

Recent evidence has highlighted the impact of glycemic control on the incidence and progression of diabetic micro- and macrovascular complications, and on cardiovascular risk in the non-diabetic population. Postprandial blood glucose concentrations make a major contribution to overall glycemic control, and are determined in part by upper gastrointestinal function. Conversely, poor glycemic control has an acute, reversible effect on gastrointestinal motility. Insights into the mechanisms by which the gut contributes to glycemia have given rise to a number of novel dietary and pharmacological strategies designed to lower postprandial blood glucose concentrations.

Figure 1

Relationship between the blood glucose concentration 10 min after consuming 75 g glucose in 300 mL water, and the gastric half-emptying time (T50) in patients with type 2 diabetes (open squares, r = -0.67, P < 0.005) and healthy subjects (filled circles, r = -0.56, P < 0.05). Adapted from Jones et al 1996[28].

Figure 2

Effects of erythromycin (200 mg iv, filled circles) and morphine (8 mg iv, open squares) compared to placebo (open triangles) on (A) solid and (B) liquid gastric emptying and (C) blood glucose concentration in 9 patients with type 2 diabetes. ^aP < 0.05, ^bP < 0.01 vs placebo. Adapted from Gonlachanvit et al 2003[29].

Figure 3

Effect of initially more rapid intraduodenal glucose infusion (3 kcal/min between t = 0 and 15 min and 0.71 kcal/min between t = 15 and 120 min) (closed symbols) compared to constant infusion (1 kcal/min between t = 0 and 120 min) (open symbols) in healthy subjects (triangles) and patients with type 2 diabetes (circles) on (A) blood glucose, (B) plasma insulin, (C) plasma GLP-1, and (D) plasma GIP. Each pair of curves differs between 0 and 30 min for variable vs constant intraduodenal infusion (P < 0.05). Adapted from O’Donovan et al 2004[52].

Figure 4

Solid and liquid gastric emptying in (A) healthy subjects and (B) patients with type 1 diabetes mellitus during euglycemia (blood glucose 4 mmol/L) and “physiological” hyperglycemia (blood glucose 8 mmol/L). Adapted from Schvarcz et al 1997[82].