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Moradian A, Goonatilleke E, Lin TT, Hatten-Beck M, Emrick M, Schepmoes AA, Fillmore TL, MacCoss MJ, Sechi S, Sobhani K, Little R, Kabytaev K, van Eyk JE, Qian WJ, Hoofnagle AN. Interlaboratory Comparison of Antibody-Free LC-MS/MS Measurements of C-peptide and Insulin. Clin Chem 2024; 70:855-864. [PMID: 38549041 DOI: 10.1093/clinchem/hvae034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2023] [Accepted: 01/29/2024] [Indexed: 05/01/2024]
Abstract
BACKGROUND The enhanced precision and selectivity of liquid chromatography-tandem mass spectrometry (LC-MS/MS) makes it an attractive alternative to certain clinical immunoassays. Easily transferrable work flows could help facilitate harmonization and ensure high-quality patient care. We aimed to evaluate the interlaboratory comparability of antibody-free multiplexed insulin and C-peptide LC-MS/MS measurements. METHODS The laboratories that comprise the Targeted Mass Spectrometry Assays for Diabetes and Obesity Research (TaMADOR) consortium verified the performance of a validated peptide-based assay (reproducibility, linearity, and lower limit of the measuring interval [LLMI]). An interlaboratory comparison study was then performed using shared calibrators, de-identified leftover laboratory samples, and reference materials. RESULTS During verification, the measurements were precise (2.7% to 3.7%CV), linear (4 to 15 ng/mL for C-peptide and 2 to 14 ng/mL for insulin), and sensitive (LLMI of 0.04 to 0.10 ng/mL for C-peptide and 0.03 ng/mL for insulin). Median imprecision across the 3 laboratories was 13.4% (inter-quartile range [IQR] 11.6%) for C-peptide and 22.2% (IQR 20.9%) for insulin using individual measurements, and 10.8% (IQR 8.7%) and 15.3% (IQR 14.9%) for C-peptide and insulin, respectively, when replicate measurements were averaged. Method comparison with the University of Missouri reference method for C-peptide demonstrated a robust linear correlation with a slope of 1.044 and r2 = 0.99. CONCLUSIONS Our results suggest that combined LC-MS/MS measurements of C-peptide and insulin are robust and adaptable and that standardization with a reference measurement procedure could allow accurate and precise measurements across sites, which could be important to diabetes research and help patient care in the future.
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Affiliation(s)
- Annie Moradian
- Precision Biomarker Laboratories, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Elisha Goonatilleke
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States
| | - Tai-Tu Lin
- Integrative Omics, Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Maya Hatten-Beck
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States
| | - Michelle Emrick
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States
| | - Athena A Schepmoes
- Integrative Omics, Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Thomas L Fillmore
- Integrative Omics, Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Michael J MacCoss
- Department of Genome Sciences, University of Washington, Seattle, WA, United States
| | - Salvatore Sechi
- Division of Diabetes, Endocrinology, & Metabolic Diseases, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD, United States
| | - Kimia Sobhani
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Randie Little
- Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine, Columbia, MO, United States
| | - Kuanysh Kabytaev
- Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine, Columbia, MO, United States
| | - Jennifer E van Eyk
- Precision Biomarker Laboratories, Cedars-Sinai Medical Center, Los Angeles, CA, United States
- Department of Pathology and Laboratory Medicine, Cedars-Sinai Medical Center, Los Angeles, CA, United States
- Advanced Clinical Biosystems Research Institute, Smidt Heart Institute, Cedars-Sinai Medical Center, Los Angeles, CA, United States
| | - Wei-Jun Qian
- Integrative Omics, Biological Sciences Division, Pacific Northwest National Laboratory, Richland, WA, United States
| | - Andrew N Hoofnagle
- Department of Laboratory Medicine and Pathology, University of Washington, Seattle, WA, United States
- Department of Medicine, Kidney Research Institute, University of Washington, Seattle, WA, United States
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Four features of temporal patterns characterize similarity among individuals and molecules by glucose ingestion in humans. NPJ Syst Biol Appl 2022; 8:6. [PMID: 35136093 PMCID: PMC8826934 DOI: 10.1038/s41540-022-00213-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 01/05/2022] [Indexed: 12/24/2022] Open
Abstract
Oral glucose ingestion induces systemic changes of many blood metabolites related not only to glucose, but also other metabolites such as amino acids and lipids through many blood hormones. However, the detailed temporal changes in the concentrations of comprehensive metabolites and hormones over a long time by oral glucose ingestion are uncharacterized. We measured 83 metabolites and 7 hormones in 20 healthy human subjects in response to glucose ingestion. We characterized temporal patterns of blood molecules by four features: (i) the decomposability into “amplitude” and “rate” components, (ii) the similarity of temporal patterns among individuals, (iii) the relation of molecules over time among individuals, and (iv) the similarity of temporal patterns among molecules. Glucose and glucose metabolism-related hormones indicated a rapid increase, and citrulline and lipids, which indicated a rapid decrease, returned to fasting levels faster than amino acids. Compared to glucose metabolism-related molecules and lipids, amino acids showed similar temporal patterns among individuals. The four features of temporal patterns of blood molecules by oral glucose ingestion characterize the differences among individuals and among molecules.
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Alvarez-Ramos P, Jimenez-Carmona S, Alemany-Marquez P, Cordoba-Doña JA, Aguilar-Diosdado M. Socioeconomic deprivation and development of diabetic retinopathy in patients with type 1 diabetes mellitus. BMJ Open Diabetes Res Care 2020; 8:e001387. [PMID: 33177040 PMCID: PMC7661358 DOI: 10.1136/bmjdrc-2020-001387] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/20/2020] [Revised: 08/24/2020] [Accepted: 09/05/2020] [Indexed: 01/08/2023] Open
Abstract
INTRODUCTION Very little is known about the influence of socioeconomic status on type 1 diabetes mellitus (T1DM) complications. Our aim was to determine whether socioeconomic level is a risk factor for the development of diabetic retinopathy (DR) in patients with T1DM. RESEARCH DESIGN AND METHODS A cohort of 150 patients with T1DM were studied prospectively over 9 years. Socioeconomic status was assessed using a neighborhood-level measure based on an index of deprivation. The contribution of other variables such as hypertension, dyslipidemia, diabetic nephropathy and smoking habit was evaluated. Cox proportional hazards models were used to quantify the associations. RESULTS The incidence of DR was 21.6 cases per 1000 patient-years. Multivariable analyses showed that for each percentage point increase in glycated hemoglobin (HbA1c), the risk of developing DR increased by 58% (HR 1.58, 95% CI 1.19 to 2.10).Patients with T1DM onset >18 years of age and resident in areas of lower socioeconomic levels presented with almost triple the risk of developing DR (HR 2.95, 95% CI 1.08 to 8.00) compared with those with onset <18 years of age and resident in less deprived areas. We did not find significant relationships with other variables studied such as hypertension, dyslipidemia, diabetic nephropathy and smoking habit. CONCLUSIONS Low socioeconomic level is a risk factor, independent of glycemic control, in the development of DR in patients with T1DM when the onset of diabetes is in adulthood. This finding indicates that socioeconomic status and age of onset need to be considered in population screening for DR in patients with T1DM.
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Affiliation(s)
- Pablo Alvarez-Ramos
- Ophtalmology Department, Hospital Universitario Puerta del Mar, Cadiz, Spain
| | - Soledad Jimenez-Carmona
- Ophtalmology Department, Hospital Universitario Puerta del Mar, Cadiz, Spain
- Surgery Department, Universidad de Cádiz Facultad de Medicina, Cadiz, Spain
- Research Institute of Biomedicine of Cadiz (INiBICA), Cadiz, Spain
| | - Pedro Alemany-Marquez
- Ophtalmology Department, Hospital Universitario Puerta del Mar, Cadiz, Spain
- Surgery Department, Universidad de Cádiz Facultad de Medicina, Cadiz, Spain
- Research Institute of Biomedicine of Cadiz (INiBICA), Cadiz, Spain
| | - Juan Antonio Cordoba-Doña
- Research Institute of Biomedicine of Cadiz (INiBICA), Cadiz, Spain
- Public Health Department, Hospital Universitario de Jerez de la Frontera, Jerez de la Frontera, Spain
| | - Manuel Aguilar-Diosdado
- Research Institute of Biomedicine of Cadiz (INiBICA), Cadiz, Spain
- Endocrinology and Nutrition Department, Hospital Universitario Puerta del Mar, Universidad de Cadiz, Cadiz, Spain
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Salih JM, Abdulateef DS. Detection of C-peptide in human hair and nail: a comparison between healthy persons and persons with type 1 diabetes. BMJ Open Diabetes Res Care 2020; 8:e001297. [PMID: 32675173 PMCID: PMC7368469 DOI: 10.1136/bmjdrc-2020-001297] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Revised: 06/11/2020] [Accepted: 06/16/2020] [Indexed: 01/12/2023] Open
Abstract
OBJECTIVES Serum and urinary C-peptide has clinical implications in people with/without diabetes. Recently, C-peptide was detected in hair samples of healthy adults but not studied in people with diabetes. It is not known whether C-peptide can be detectable in nail tissue or not. This study aims to assess the detection of C-peptide in hair and nail samples and to find whether hair and nail C-peptide levels are different in type 1 diabetes mellitus (T1DM) compared with healthy individuals. RESEARCH DESIGN AND METHODS In a prospective case-control study on 41 subjects with T1DM and 42 control subjects, hair and nail samples were collected and prepared. C-peptide was extracted by incubating the samples with methanol and measuring the extract with an immunoassay. The hair and nail C-peptide values were compared between the T1DM and control group and their correlations with each other and with other variables were assessed with a significant level set at 0.05. RESULTS Hair and nail C-peptide levels were detected in both groups, with significantly lower values in T1DM compared with the control group. T1DM with >7-year diabetes duration had significantly lower C-peptide in serum, nails and hair. Hair and nail C-peptide levels have significant positive correlations with each other and negative correlations with age. CONCLUSIONS We conclude that C-peptide are detectable in the hair and nails of healthy persons and persons with T1DM. Compared with the healthy persons, persons with T1DM had significantly lower hair and nail C-peptide and significant hair/nail C-peptide reduction after 7 years of diagnosis. Our results suggest that hair and nails are suitable matrices for the measurement of C-peptide in healthy persons and persons with T1DM.
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Affiliation(s)
- Jamal M Salih
- Physiology, University of Sulaimani College of Medicine, Sulaimani, Kurdistan, Iraq
| | - Darya S Abdulateef
- Physiology, University of Sulaimani College of Medicine, Sulaimani, Kurdistan, Iraq
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Abdulateef DS, Salih JM. Detection of C-Peptide in Scalp Hair of Healthy Adults. Diabetes Metab Syndr Obes 2020; 13:227-236. [PMID: 32099429 PMCID: PMC7006852 DOI: 10.2147/dmso.s240785] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 01/21/2020] [Indexed: 12/14/2022] Open
Abstract
PURPOSE The C-peptide level from blood and urine samples represents endogenous insulin secretion and has clinical implications for individuals with and without diabetes. However, the study results are inconsistent and the available methods can only measure short-term C-peptide levels, which can be substantially affected by concurrent glycaemia. In this study, we evaluated whether C-peptide can be detected from hair? Hair C-peptide if detected could potentially represent long-term, insulin secretion. And to know whether there is any correlation between hair C-peptide with certain biochemical and demographic parameters. METHODS In a prospective observational study on 120 normal healthy individuals, hair samples were taken from the scalp and C-peptide was extracted. The hair C-peptide levels were measured in pg/mg of hair using electrochemiluminescence immunoassay (ECLISA) after methanol extraction and were compared among different age and body-type groups. Serum C-peptide, fasting plasma glucose (FPG) and HbA1c were assessed and their levels were correlated with anthropometric parameters. RESULTS A detectable range of C-peptide was found in the hair samples of all the subjects with a median of 63.59 pg/mg hair and it was positively correlated with FPG but no significant correlation was found between hair C-peptide and serum C-peptide levels. The hair C-peptide level, along with FPG and HbA1c, was significantly different according to age. CONCLUSION These results conclude that C-peptide can be detected from and measured in the scalp hair of humans and it is positively correlated with FPG, and it is significantly different according to age. This technique, if validated, may verify its usefulness in future studies of both healthy and diseased subjects.
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Affiliation(s)
- Darya S Abdulateef
- Physiology Department, College of Medicine, University of Sulaimani, Sulaymaniyah, Kurdistan Region, Iraq
| | - Jamal M Salih
- Physiology Department, College of Medicine, University of Sulaimani, Sulaymaniyah, Kurdistan Region, Iraq
- Diabetes Physician, Diabetes and Endocrine Centre, Sulaymaniyah, Kurdistan Region, Iraq
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Stevenson MJ, Farran IC, Uyeda KS, San Juan JA, Heffern MC. Analysis of Metal Effects on C-Peptide Structure and Internalization. Chembiochem 2019; 20:2447-2453. [PMID: 31074079 DOI: 10.1002/cbic.201900172] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2019] [Indexed: 01/17/2023]
Abstract
The connecting peptide (C-peptide) has received increased attention for its potential therapeutic effects in ameliorating illnesses such as kidney disease and diabetes. Although the mechanism of C-peptide signaling remains elusive, evidence supports its internalization and intracellular function. Emerging research is uncovering the diverse biological roles metals play in controlling and affecting the function of bioactive peptides. The work presented herein investigates interactions between C-peptide and first-row d-block transition metals, as well as their effects on C-peptide internalization into cells. Through spectroscopic techniques, it is demonstrated that CrIII , CuII , and ZnII bind to C-peptide with differing stoichiometries and biologically relevant affinities. In addition, metal binding elicits both subtle changes in secondary structure and inhibits adoption of an α-helical character in environments where the dielectric constants are reduced. This study shows how metal ions can modulate peptide hormone activity through subtle structural changes to disrupt cellular uptake.
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Affiliation(s)
- Michael J Stevenson
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Ian C Farran
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Kylie S Uyeda
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Jessica A San Juan
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA, 95616, USA
| | - Marie C Heffern
- Department of Chemistry, University of California, One Shields Avenue, Davis, CA, 95616, USA
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7
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Little RR, Wielgosz RI, Josephs R, Kinumi T, Takatsu A, Li H, Stein D, Burns C. Implementing a Reference Measurement System for C-Peptide: Successes and Lessons Learned. Clin Chem 2017; 63:1447-1456. [PMID: 28646033 PMCID: PMC5575958 DOI: 10.1373/clinchem.2016.269274] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 04/25/2017] [Indexed: 12/12/2022]
Abstract
BACKGROUND Assessment of endogenous insulin secretion by measuring C-peptide concentrations is widely accepted. Recent studies have shown that preservation of even small amounts of endogenous C-peptide production in patients with type 1 diabetes reduces risks for diabetic complications. Harmonization of C-peptide results will facilitate comparison of data from different research studies and later among clinical laboratory results at different sites using different assay methods. CONTENT This review provides an overview of the general process of harmonization and standardization and the challenges encountered with implementing a reference measurement system for C-peptide. SUMMARY Efforts to harmonize C-peptide results are described, including those by the National Institute of Diabetes and Digestive and Kidney Diseases-led C-peptide Standardization Committee in the US, activities in Japan, efforts by the National Institute for Biological Standards and Control in the UK, as well as activities led by the Bureau International des Poids et Mesures and the National Metrology Institute in China. A traceability scheme is proposed along with the next steps for implementation. Suggestions are made for better collaboration to optimize the harmonization process for other measurands.
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Affiliation(s)
- Randie R Little
- Department of Pathology and Anatomical Sciences, University of Missouri School of Medicine, Columbia, MO;
| | | | - Ralf Josephs
- Bureau International des Poids et Mesures, Sèvres Cedex, France
| | - Tomoya Kinumi
- Bio-Medical Standards Group, National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Ibaraki, Japan
| | - Akiko Takatsu
- Bio-Medical Standards Group, National Metrology Institute of Japan, National Institute of Advanced Industrial Science and Technology, Ibaraki, Japan
| | - Hongmei Li
- National Institute of Metrology, Beijing, China
| | - Daniel Stein
- Division of Endocrinology and Metabolism, Diabetes Research and Training Center, Albert Einstein College of Medicine, Yeshiva University, Bronx, NY
| | - Chris Burns
- National Institute for Biological Standards and Control, South Mimms, UK
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8
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Park JS, Kim CS, Nam JY, Kim DM, Jo MH, Park J, Ahn CW, Cha BS, Lim SK, Kim KR, Lee HC, Huh KB. Characteristics of type 2 diabetes in terms of insulin resistance in Korea. Yonsei Med J 2005; 46:484-90. [PMID: 16127772 PMCID: PMC2815832 DOI: 10.3349/ymj.2005.46.4.484] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The aim of this study was to assess the implications of insulin resistance on the clinical and biochemical profiles of Korean type 2 diabetic patients. 122 patients with type 2 diabetes underwent a short insulin tolerance test to assess insulin resistance. Subjects were classified in tertiles according to ISI (insulin sensitivity index), and the tertile I (the insulin- resistant group) and tertile III (the insulin-sensitive group) clinical and biochemical parameters were compared. Age, waist circumference (WC), systolic blood pressure (SBP), HbA1c, body fat content, and fasting plasma glucose were significantly higher in tertile I than tertile III (all p < 0.05). The frequency of hypertension and family history of cerebrovascular disease (CVD) were greater in tertile I than III (p < 0.05). To evaluate the factors affecting ISI, multiple regression was performed, and age, WC, SBP, HbA1c, and body fat content were found to be independently related to insulin resistance (p < 0.05). Old age, hypertension, central obesity, and poor glycemic control were identified as clinical parameters of insulin resistance in Korean type 2 diabetic patients.
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Affiliation(s)
- Jong-Suk Park
- Division of Endocrinology, Department of Internal Medicine, Yongdong Severance Hospital, Yonsei University College of Medicine, 146-92 Dogok-dong, Gangnam-gu, Seoul 135-720, Korea.
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9
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Ahn CW, Kim HS, Nam JH, Song YD, Lim SK, Kim KR, Lee HC, Huh KB. Clinical characteristics, GAD antibody (GADA) and change of C-peptide in Korean young age of onset diabetic patients. Diabet Med 2002; 19:227-33. [PMID: 11918625 DOI: 10.1046/j.1464-5491.2002.00670.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
AIMS To investigate the association of clinical and immunological markers with diabetes classification in newly diagnosed young diabetic patients at disease onset. METHODS Eighty-two diabetic patients recruited within 1 year of onset (mean age 23.0 +/- 7.1, M:F = 46:36) were divided into three groups, namely: a low fasting C-peptide (FC) level at baseline group (the low FC group (n = 14, FC < 0.18 nmol/l)), an intermediate FC group (n = 29, 0.18 nmol/l < or = FC < 0.37 nmol/l), and a high FC group (n = 39, 0.37 nmol/l < or = FC). Patients were reclassified at follow-up (mean follow-up period 3.7 +/- 1.4 years) in the same manner as described above into low FC group (n = 31), intermediate FC group (n = 20), and high FC group (n = 31). The clinical characteristics and prevalence of GADA were compared. RESULTS Patients in the high FC group at baseline had a higher body mass index (BMI), a higher frequency of a family history of diabetes, a higher meal-stimulated C-peptide increment, a lower frequency of ketonuria, a lower frequency of history of diabetic ketoacidosis, and a lower frequency of insulin therapy at diagnosis than those in the low and intermediate FC groups at baseline. Insulin secretory capacity, which was represented by fasting C-peptide, was affected by BMI at diagnosis and the presence of GADA. All the patients of the low FC group on follow-up were finally classified as having Type 1 diabetes; moreover, the factors that determined the type of diabetes were lower BMI at onset, GADA positivity, insulin therapy, lower fasting C-peptide level and lower meal-stimulated C-peptide increment at initial admission. CONCLUSIONS Our study suggests that follow-up involving C-peptide and GADA measurements in combination with clinical characteristics is useful for discriminating between the types of diabetes in these groups.
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Affiliation(s)
- C W Ahn
- Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea.
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Affiliation(s)
- P M Clark
- Regional Endocrine Laboratory, University Hospital Birmingham NHS Trust, Selly Oak Hospital, UK.
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11
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Prior MJ, Prout T, Miller D, Ewart R, Kumar D. C-peptide and the classification of diabetes mellitus patients in the Early Treatment Diabetic Retinopathy Study. Report number 6. The ETDRS Research Group. Ann Epidemiol 1993; 3:9-17. [PMID: 8287162 DOI: 10.1016/1047-2797(93)90004-n] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The Early Treatment Diabetic Retinopathy Study (ETDRS), conducted at 22 clinical centers during the period 1980 to 1989, collected baseline data on C-peptide levels after ingestion of Sustacal in 582 patients with diabetes mellitus, prior to enrollment in the trial. Data on several clinical factors associated with diabetes were also collected from all 3711 enrolled patients. C-peptide data were used to develop sets of clinical criteria for the classification of ETDRS patients and to compare and contrast definitions of type of diabetes used in previous studies. The distribution of C-peptide levels was strikingly bimodal, suggesting a division of study participants into two groups--those with levels at 80 pmol/L or less and those with more than 80 pmol/L of C-peptide after Sustacal ingestion. Constellations of clinical characteristics that could serve as proxies for C-peptide level were ascertained. The result was two sets of clinically developed definitions for type of diabetes in the ETDRS. According to the more restrictive set of definitions, three groups were identified, compared to two groups using the "broad" set of definitions. Discriminant analysis was also used to classify ETDRS patients, yielding similar results. A comparison of definitions of type of diabetes used in the ETDRS and in previous studies revealed that even in the absence of C-peptide data, clinically derived definitions provided good discrimination between type I and type II diabetes.
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Affiliation(s)
- M J Prior
- Early Treatment Diabetic Retinopathy Study (ETDRS) Coordinating Center, Maryland Medical Research Institute, Baltimore, MD 21210
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Corral J, Miralles JM, García-Pascual IJ, Corrales JJ, García-Sastre A, Villar E. Increased serum N-acetyl-beta-D-glucosaminidase and alpha-D-mannosidase activities in obese subjects. THE CLINICAL INVESTIGATOR 1992; 70:880-4. [PMID: 1450611 DOI: 10.1007/bf00180432] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
We have studied N-acetyl-beta-D-glucosaminidase and alpha-D-mannosidase activities in human sera from 35 control subjects, 47 normo- and hyperinsulinemic obese persons, and 12 diabetic patients after a fasting period of 12 h and at 30, 60, 90, and 120 min after an oral glucose overload. The results show a significantly higher activity of these 2 enzymes in obese subjects and diabetic patients, of similar magnitude, especially in those obese persons with a higher grade of obesity. Moreover, the activity of these glycosidases decreases in a similar way in all these 3 groups after the oral glucose overload.
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Affiliation(s)
- J Corral
- Departamento de Bioquímica y Biología Molecular, Facultad de Biología, Universidad de Salamanca
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Collins JE, Leonard JV, Teale D, Marks V, Williams DM, Kennedy CR, Hall MA. Hyperinsulinaemic hypoglycaemia in small for dates babies. Arch Dis Child 1990; 65:1118-20. [PMID: 2248501 PMCID: PMC1792359 DOI: 10.1136/adc.65.10.1118] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Blood glucose concentrations were measured prospectively in 27 small for dates infants in the first 48 hours after birth: 10 infants became hypoglycaemic. Of these, five had inappropriately raised plasma insulin concentrations. Plasma free fatty acids were lower and carbohydrate intake higher in these five infants, further supporting the diagnosis of hyperinsulinism. The hypoglycaemia recurred in four of the five hyperinsulinaemic infants, but in none of those who were not hyperinsulinaemic. Hyperinsulinism is common in small for dates babies. It is important to recognise this because hypoglycaemia is likely to recur and appropriate treatment is needed to prevent long term sequelae.
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Affiliation(s)
- J E Collins
- Department of Child Health, Institute of Child Health, London
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Gjessing HJ, Matzen LE, Faber OK, Frøland A. Fasting plasma C-peptide, glucagon stimulated plasma C-peptide, and urinary C-peptide in relation to clinical type of diabetes. Diabetologia 1989; 32:305-11. [PMID: 2666217 DOI: 10.1007/bf00265547] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Many patients with Type 2 (non-insulin-dependent) diabetes mellitus are treated with insulin in order to control hyperglycaemia. We studied fasting plasma C-peptide, glucagon stimulated plasma C-peptide, and 24 h urinary C-peptide in relation to clinical type of diabetes in 132 insulin treated diabetic subjects. Patients were classified clinically as Type 1 (insulin-dependent) diabetic subjects in the presence of at least two of the following criteria: 1) significant ketonuria, 2) insulin treatment started within one year after diagnosis, 3) age of diagnosis less than or equal to 40 years, and 4) weight below 110% of ideal weight of the same age and sex. Eighty patients were classified as Type 1 and 52 as Type 2 diabetic subjects. A second classification of patients into 6 C-peptide classes was then performed. Class I consisted of patients without islet B-cell function. Class II-VI had preserved islet B-cell function and were separated according to the 20%, 40%, 60% and 80% C-peptide percentiles. The two classifications of patients were compared by calculating the prevalence of clinical Type 1 and Type 2 diabetes in each of the C-peptide classes. This analysis showed that patients with a fasting plasma C-peptide value less than 0.20 nmol/l, a glucagon stimulated plasma C-peptide value less than 0.32 nmol/l, and a urinary C-peptide value less than 3.1 nmol/l, or less than 0.54 nmol/mmol creatinine/24 h, or less than 5.4 nmol/24 h mainly were Type 1 diabetic patients; while patients with C-peptide levels above these values mainly were Type 2.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H J Gjessing
- Medical Department, Fredericia Hospital, Denmark
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Malmquist J, Birgerstam G. Assays of pancreatic B cell secretory products: utility in investigative and clinical diabetology. Scand J Clin Lab Invest 1986; 46:705-13. [PMID: 3541145 DOI: 10.3109/00365518609084041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
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Grant PJ, Barlow E, Miles DW. Plasma C-peptide levels identify insulin-treated diabetic patients suitable for oral hypoglycaemic therapy. Diabet Med 1984; 1:284-6. [PMID: 6242818 DOI: 10.1111/j.1464-5491.1984.tb01974.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Plasma C-peptide levels were measured fasting and 2 h after an oral glucose load in 37 insulin-treated diabetic patients to assess their clinical value in identifying any noninsulin-dependent diabetic patients. All subjects were changed from insulin to oral hypoglycaemic therapy and followed for 3 months. Twenty patients (group A) completed the trial without requiring insulin and 17 (group B) required restabilization on insulin due to deteriorating metabolic control. Fasting and 2 h C-peptide levels were significantly higher in group A (0.11 +/- 0.09 and 0.17 +/- 0.12 nmol/l; mean +/- S.D.) compared with group B (0.02 +/- 0.03 and 0.02 +/- 0.03 nmol/l) (p less than 0.002 and p less than 0.002). The fasting C-peptide levels at 3 months (0.28 +/- 0.14 nmol/l) were also significantly higher than the fasting levels at the beginning of the study (p less than 0.002). Fasting and 2-h glucose levels were lower in group A (11.0 +/- 3.7 and 17.6 +/- 5.2 mmol/l) than in group B (14.4 +/- 6.2 and 23.1 +/- 5.9 mmol/l; p less than 0.05 and 0.02, respectively). The differences in glycosylated haemoglobin and fasting glucose levels at the start of the study and after 3 months of oral therapy were not statistically significant. Although C-peptide values overlapped in groups A and B, they were of greater value in identifying patients suitable for oral therapy than any single clinical criterion, and thus may help in identifying insulin-treated diabetic patients who may be treated with oral therapy without deterioration in metabolic control.
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Affiliation(s)
- P J Grant
- Airedale General Hospital, Steeton, W. Yorkshire, U.K
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Abstract
A 70-year-old woman with insulin dependent diabetes mellitus presented with symptoms suggestive of senile dementia. Outpatient assessment failed to reveal poor diabetic control with frequent nocturnal hypoglycaemia. Eventual appreciation of the poor control resulted in several failed attempts at improving therapy with various subcutaneous insulin regimes. Intramuscular and intravenous routes produced acceptable blood glucose levels with striking reversal of the patient's symptoms. The possible causes of nocturnal hypoglycaemia in this patient are discussed.
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Garcia-Webb P, Bottomley S, Bonser AM. Instability of C-peptide reactivity in plasma and serum stored at -20 degrees C. Clin Chim Acta 1983; 129:103-6. [PMID: 6851148 DOI: 10.1016/0009-8981(83)90157-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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