Ying Yang1, Min Wang1, Jingzhi Tong1, Zuoliang Dong2, Min Deng3, Xiaojun Ren1, Hui Li1, Jing Yang1, Zhaowei Meng4, Jinhong Sun5, Qing He1, Ming Liu1. 1. Department of Endocrinology and Metabolism, Tianjin Medical University General Hospital, Tianjin, China. 2. Department of Medical Laboratory, Tianjin Medical University General Hospital, Tianjin, China. 3. Department of Physical Examination, Tianjin Electric Power Hospital, Tianjin, China. 4. Department of Nuclear Medicine, Tianjin Medical University General Hospital, Tianjin, China. 5. Department of Health Management, Tianjin Medical University General Hospital, Tianjin, China.
Abstract
CONTEXT: Evidence indicates that there is substantial impairment/loss of β-cell function/mass even before prediabetes. Elevated plasma proinsulin is a sign of β-cell dysfunction in patients with diabetes/prediabetes. However, the dynamic changes of glucose stimulated proinsulin secretion (GSPS) among nondiabetic individuals remain obscure. OBJECTIVE: To examine GSPS and glucose-stimulated insulin secretion (GSIS) among individuals with normal glucose tolerance (NGT) and impaired glucose tolerance (IGT) and to evaluate whether impaired GSPS is an early biomarker of β-cell impairment in individuals with NGT who have subthreshold postprandial plasma glucose (PPG). DESIGN AND PARTICIPANTS: We evaluated GSPS and GSIS in 116 Chinese adults without diabetes (mean age ± SD, 33.31 ± 9.10 years; mean BMI, 25.24 ± 4.20 kg/m2) with fasting plasma glucose (FPG) < 5.6 mmol/L. Based on 2hPPG, the participants were divided into three groups: NGT1 (2hPPG < 6.67 mmol/L), NGT2 (6.67 ≤ 2hPPG < 7.78 mmol/L), and IGT (7.78 ≤ 2hPPG<11.1 mmol/L). We analyzed the association of GSIS and GSPS with commonly used indexes of β-cell function, insulin resistance and family history of diabetes. RESULTS: Although not diagnosed with prediabetes, the individuals with NGT2 have clinical characteristics and high diabetes risk factors similar to those of the IGT group. However, unlike individuals with IGT, NGT2 participants did not exhibit a delayed GSIS. Instead, GSPS was impaired in NGT2 groups but not in NGT1 group. CONCLUSIONS: This study suggests that impaired GSPS, but not impaired GSIS, may serve as an early biomarker to identify a subpopulation of NGT with a high risk of diabetes.
CONTEXT: Evidence indicates that there is substantial impairment/loss of β-cell function/mass even before prediabetes. Elevated plasma proinsulin is a sign of β-cell dysfunction in patients with diabetes/prediabetes. However, the dynamic changes of glucose stimulated proinsulin secretion (GSPS) among nondiabetic individuals remain obscure. OBJECTIVE: To examine GSPS and glucose-stimulated insulin secretion (GSIS) among individuals with normal glucose tolerance (NGT) and impaired glucose tolerance (IGT) and to evaluate whether impaired GSPS is an early biomarker of β-cell impairment in individuals with NGT who have subthreshold postprandial plasma glucose (PPG). DESIGN AND PARTICIPANTS: We evaluated GSPS and GSIS in 116 Chinese adults without diabetes (mean age ± SD, 33.31 ± 9.10 years; mean BMI, 25.24 ± 4.20 kg/m2) with fasting plasma glucose (FPG) < 5.6 mmol/L. Based on 2hPPG, the participants were divided into three groups: NGT1 (2hPPG < 6.67 mmol/L), NGT2 (6.67 ≤ 2hPPG < 7.78 mmol/L), and IGT (7.78 ≤ 2hPPG<11.1 mmol/L). We analyzed the association of GSIS and GSPS with commonly used indexes of β-cell function, insulin resistance and family history of diabetes. RESULTS: Although not diagnosed with prediabetes, the individuals with NGT2 have clinical characteristics and high diabetes risk factors similar to those of the IGT group. However, unlike individuals with IGT, NGT2 participants did not exhibit a delayed GSIS. Instead, GSPS was impaired in NGT2 groups but not in NGT1 group. CONCLUSIONS: This study suggests that impaired GSPS, but not impaired GSIS, may serve as an early biomarker to identify a subpopulation of NGT with a high risk of diabetes.