Proinsulin associates with poor β-cell function, glucose-dependent insulinotropic peptide, and insulin resistance in persistent type 2 diabetes after Roux-en-Y gastric bypass in humans

Abstract

Background: The determinants of type 2 diabetes (T2D) remission and/or relapse after gastric bypass (RYGB) remain fully unknown. This study characterized β- and α-cell function, in cretin hormone release and insulin sensitivity in individuals with (remitters) or without (non-remitters) diabetes remission after RYGB.

Methods: This is a cross-sectional study of two distinct cohorts of individuals with or without diabetes remission at least 2 years after RYGB. Each individual underwent-either an oral glucose (remitters) or a mixed meal (non-remitters) test; glucose, proinsulin, insulin, C-peptide, glucagon, incretins and leptin were measured.

Results: Compared to remitters (n = 23), non-remitters (n = 31) were older (mean [±SD] age 56.1 ± 8.2 vs. 46.0 ± 8.9 years, P < 0.001), had longer diabetes duration (13.1 ± 10.1 vs. 2.2 ± 2.4 years, P < 0.001), were further out from the surgery (5.6 ± 3.3 vs. 3.5 ± 1.7 years, P < 0.01), were more insulin resistant (HOMA-IR 4.01 ± 3.65 vs. 2.08 ± 1.22, P < 0.001), but did not differ for body weight. As predicted, remitters had higher β-cell glucose sensitivity (1.95 ± 1.23 vs. 0.86 ± 0.55 pmol/kg/min/mmol, P < 0.001) and disposition index (1.55 ± 1.75 vs 0.33 ± 0.27, P = 0.003), compared to non-remitters, who showed non-suppressibility of glucagon during the oral challenge (time × group P = 0.001). Higher proinsulin (16.55 ± 10.45 vs. 6.62 ± 3.50 PM, P < 0.0001), and proinsulin: C-peptide (40.83 ± 29.43 vs. 17.13 ± 7.16, P < 0.001) were strongly associated with non-remission status, while differences in incretins between remitters and non-remitters were minimal.

Conclusions: Individual without diabetes remission after gastric bypass have poorer β-cell response and lesser suppression of glucagon to an oral challenge; body weight and incretins differ minimally according to remission status.

Keywords: diabetes remission; gastric bypass; incretins; proinsulin; β-Cell function; β细胞功能。; 糖尿病缓解; 肠促胰岛素; 胃旁路; 胰岛素原.

FIGURE 1

Metabolic and hormone responses during the oral challenge in individuals with (remitters) and without (non-remitters) type 2 diabetes remission after Rouxen-Y gastric bypass. Data are the mean ± SEM. *P < 0.05 tested by GLM with repeated measures, if time ×8 group interaction was significant. A, glucose; B, insulin secretion rate (ISR); C, proinsulin; D, C-peptide; E, glucose-dependent insulinotropic polypeptide (GIP); F, glucagon-like peptide-1 (GLP-1); G, glucagon; H, disposition index, represented by the relationship between β-cell glucose sensitivity (BCGS) and the homeostatic model assessment of insulin resistance (HOMA-IR)

FIGURE 2

Metabolic and hormone responses during the oral challenge, adjusted for glucose concentrations, in remitters and non-remitters. Data are the mean ± SEM. *P < 0.05 GLM with repeated measures, with significant time × group interaction. A, insulin secretion rate (ISR); B, proinsulin; C, C-peptide; D, glucagon; E, glucose-dependent insulinotropic polypeptide (GIP); F, glucagon-like peptide-1 (GLP-1)