Intact GLP-1 levels and type 2 diabetes risk

Introduction

Glucagon-like peptide-1 (GLP-1) is an incretin hormone that enhances insulin secretion and inhibits glucagon release, making it central to glucose homeostasis. A 2014 case–control study by Lastya and colleagues examined whether fasting and post-prandial levels of intact GLP-1 were associated with type 2 diabetes mellitus (T2DM) in an Indonesian population.

Study design and methods

• Type: Case–control study conducted at Sanglah Hospital in Denpasar, Bali, between February and April 2014.
• Participants: 40 native Indonesian adults aged 18–70 — 20 with diagnosed T2DM and 20 controls with normal glucose tolerance (NGT).
• Measurements: fasting intact GLP-1 (FGLP-1), GLP-1 one hour after a 75 g glucose load (1hGLP-1), and the change between the two (ΔGLP-1).
• Thresholds: low levels were defined as FGLP-1 <2.21 pg/L, 1hGLP-1 <2.57 pg/L, and ΔGLP-1 <0.029 pg/L, based on the NGT group mean minus one standard deviation.
• Analysis: Mann–Whitney and chi-square tests with odds ratios, significance set at p < 0.05.

Findings

GLP-1 levels compared

• Fasting GLP-1 was significantly lower in the T2DM group (2.06 ± 0.43 pg/L) than in controls (2.87 ± 0.67 pg/L), p < 0.01.
• One-hour GLP-1 was also lower in T2DM (2.49 ± 0.60 pg/L) versus controls (3.42 ± 0.85 pg/L), p = 0.002.

Association with T2DM

• Fasting GLP-1: low levels occurred in 60% of T2DM subjects versus 10% of controls. OR = 13.5 (95% CI 2.434–74.867), p = 0.001.
• One-hour GLP-1: low levels occurred in 50% of T2DM subjects versus 15% of controls. OR = 5.667 (95% CI 1.254–25.606), p = 0.018.
• ΔGLP-1: no significant association (OR = 1.0, p = 1.0), although the T2DM group showed a slightly smaller change (0.43 pg/L versus 0.55 pg/L).

Results at a glance

Interpretation

Lower levels of intact GLP-1 — both fasting and after a glucose load — were strongly associated with T2DM in this cohort. That is consistent with findings across other populations showing diminished GLP-1 responses in diabetes and pre-diabetes, which may reflect impaired incretin secretion or faster degradation.

The magnitude of the GLP-1 response itself (ΔGLP-1) did not reach significance here. With only 40 participants, the study is small, and the authors frame it as a basis for further investigation rather than a settled result.

Reference

Lastya A, Saraswati MR, Suastika K. The low level of glucagon-like peptide-1 (GLP-1) is a risk factor of type 2 diabetes mellitus. BMC Res Notes. 2014;7:849. BMC Research Notes · PubMed

This article summarizes findings from a peer-reviewed publication and is informational only.