BACKGROUND: The fasting proinsulin to insulin ratio is elevated in people with type 2 diabetes and has been suggested as a marker of β-cell health. However, its utility in discriminating between individuals with varying degrees of β-cell dysfunction is unclear. Proinsulin has a very different half-life to insulin and unlike insulin does not undergo hepatic extraction prior to reaching the systemic circulation. Given these limitations, we sought to examine the relationship between fasting and postprandial concentrations of β-cell polypeptides (proinsulin, insulin and C-peptide) in people with normal and impaired glucose tolerance in differing metabolic environments. DESIGN: Subjects were studied on two occasions in random order while undergoing an oral challenge. During one study day, free fatty acids were elevated (to induce insulin resistance) by infusion of Intralipid with heparin. Proinsulin to insulin and proinsulin to C-peptide ratios were calculated for the 0-, 30-, 60- and 240-minute time points. Insulin action (Si) and β-cell responsivity (Φ) indices were calculated using the oral minimal model. RESULTS: The fasting proinsulin to c-peptide or fasting proinsulin to insulin ratios did not differ between groups and did not predict subsequent β-cell responsivity to glucose during the glycerol or Intralipid study days in either group. CONCLUSIONS: Among nondiabetic individuals, the fasting proinsulin to insulin ratio is not a useful marker of β-cell function.
BACKGROUND: The fasting proinsulin to insulin ratio is elevated in people with type 2 diabetes and has been suggested as a marker of β-cell health. However, its utility in discriminating between individuals with varying degrees of β-cell dysfunction is unclear. Proinsulin has a very different half-life to insulin and unlike insulin does not undergo hepatic extraction prior to reaching the systemic circulation. Given these limitations, we sought to examine the relationship between fasting and postprandial concentrations of β-cell polypeptides (proinsulin, insulin and C-peptide) in people with normal and impaired glucose tolerance in differing metabolic environments. DESIGN: Subjects were studied on two occasions in random order while undergoing an oral challenge. During one study day, free fatty acids were elevated (to induce insulin resistance) by infusion of Intralipid with heparin. Proinsulin to insulin and proinsulin to C-peptide ratios were calculated for the 0-, 30-, 60- and 240-minute time points. Insulin action (Si) and β-cell responsivity (Φ) indices were calculated using the oral minimal model. RESULTS: The fasting proinsulin to c-peptide or fasting proinsulin to insulin ratios did not differ between groups and did not predict subsequent β-cell responsivity to glucose during the glycerol or Intralipid study days in either group. CONCLUSIONS: Among nondiabetic individuals, the fasting proinsulin to insulin ratio is not a useful marker of β-cell function.
Authors: Teresa Mezza; Pietro M Ferraro; Vinsin A Sun; Simona Moffa; Chiara M A Cefalo; Giuseppe Quero; Francesca Cinti; Gian Pio Sorice; Alfredo Pontecorvi; Franco Folli; Andrea Mari; Sergio Alfieri; Andrea Giaccari Journal: Diabetes Date: 2018-08-21 Impact factor: 9.461
Authors: Kimberly A Placzkowski; Adrian Vella; Geoffrey B Thompson; Clive S Grant; Carl C Reading; J William Charboneau; James C Andrews; Ricardo V Lloyd; F John Service Journal: J Clin Endocrinol Metab Date: 2009-01-13 Impact factor: 5.958
Authors: Steven E Kahn; Yi-Chun Chen; Nathalie Esser; Austin J Taylor; Daniël H van Raalte; Sakeneh Zraika; C Bruce Verchere Journal: Endocr Rev Date: 2021-09-28 Impact factor: 25.261