Association between early-stage diabetic nephropathy and the delayed monophasic glucose peak during oral glucose tolerance test in type 2 diabetes mellitus.

Aims: To explore the relationships between the delayed monophasic glucose peak during oral glucose tolerance test (OGTT) and early-stage diabetic nephropathy (DN) in patients with type 2 diabetes mellitus(T2DM), and to speculate its potential as a risk factor for early-stage DN.

Materials and methods: This retrospective observational study included 448 participants, all of whom underwent a 3-h OGTT. Based on peak glucose time, they were categorized into the normal glucose tolerance (NGT) group (n = 76), the early delayed group (n = 98), and the late delayed group (n = 274) for comparison. Furthermore, T2DM patients were subdivided into the non-DN group (n = 293) and the early-stage DN group (n = 79) for comparative analysis.

Results: With the delay in glucose peak time, blood glucose levels increased, insulin secretion function and insulin sensitivity decreased. In logistic regression, ISSI-2 was independently associated with the delay in glucose peak time in patients with T2DM (OR 0.839; 95% CI 0.776-0.907; P < 0.001). Additionally, 2-h plasma glucose, OGIS, and AUC_{C-peptide0-180 min} were independently associated with delayed peak glucose time (all P < 0.001). As glucose peak time was delayed, levels of β2-microglobulin and UACR increased, and the prevalence of early-stage DN also increased (all P < 0.050). The delayed monophasic glucose peak was positively associated with early-stage DN (OR 2.230; 95% CI 1.061-4.687; P = 0.034).

Conclusions: In patients with T2DM, the delayed monophasic glucose peak during OGTT may be an early predictor of early-stage diabetes nephropathy, providing early intervention signals for our clinical work.