Phenotyping of type 2 diabetes mellitus at onset on the basis of fasting incretin tone: Results of a two-step cluster analysis

Aims/Introduction: According to some authors, in type 2 diabetes there is a reduced postprandial action of glucagon-like peptide-1 (GLP-1) and glucose-dependent insulinotropic polypeptide (GIP). However, little is known about the role of fasting incretins in glucose homeostasis. Our aim was to evaluate, through a two-step cluster analysis, the possibility of phenotyping patients with type 2 diabetes at onset on the basis of fasting GLP-1, GIP and ghrelin. Materials and Methods: A total of 96 patients with type 2 diabetes within 6 months of onset (mean age 62.40 ± 6.36 years) were cross-sectionally studied. Clinical, anthropometric and metabolic parameters were evaluated. At fasting the following were carried out: assay of GLP-1, GIP, ghrelin, insulin, C-peptide, glucagon and a panel of adipocytokines (visfatin, resistin, leptin, soluble leptin receptor and adiponectin). Results: The analysis resulted in two clusters: cluster 1 (63 patients) had significantly lower levels of GLP-1 (4.93 ± 0.98 vs 7.81 ± 1.98 pmol/L; P < 0.001), GIP (12.73 ± 9.44 vs 23.88 ± 28.56 pmol/L; P < 0.001) and ghrelin (26.54 ± 2.94 vs 39.47 ± 9.84 pmol/L; P < 0.001) compared with cluster 2 (33 patients). Between the two clusters, no differences in age, duration of disease, sex, clinical-anthropometric parameters, insulin sensitivity and adipocytokines were highlighted. However, cluster 1 was associated with significantly higher levels of glycated hemoglobin (7.4 ± 0.61 vs 6.68 ± 0.57%, P = 0.007), glucagon (232.02 ± 37.27 vs 183.33 ± 97.29 ng/L; P = 0.001), fasting glucose (7.85 ± 1.60 vs 6.93 ± 1.01 mmol/L; P = 0.003) and significantly lower levels of C-peptide (0.12 ± 0.11 vs 0.20 ± 0.20 nmol/L; P = 0.017). Conclusions: The present study suggests that fasting incretins play an important role in the pathophysiology of type 2 diabetes, which requires to further investigation.