Trajectories of fasting glucose and glycated haemoglobin in obese and non‐obese incident diabetes: Results from two large cohort studies

Abstract

AimsDiabetes development mechanisms vary by weight status. We aimed to compare cardiometabolic risk and characterize fasting plasma glucose (FPG) and glycated haemoglobin (HbA1c) trajectories before diagnosing type 2 diabetes in individuals with/without obesity.MethodsData from the China Health and Retirement Longitudinal Study (CHARLS) and English Longitudinal Study of Ageing (ELSA) were analysed. Participants without diabetes and with a body mass index of 18.5‐40 kg/m2 at baseline were included. Incident diabetes was ascertained by self‐reported physician diagnosis and/or antidiabetic drug use, FPG ≥126 mg/dl and/or HbA1c ≥6.5%. The difference in the FPG/HbA1c trajectory before the diabetes diagnosis in participants with/without obesity was examined using mixed‐effects models.ResultsAmong 11 925 eligible participants, 1361 incident diabetes cases (mean age: 61.4 years; male: 46.2%) were identified within 15 years of follow‐up. Obese diabetes showed higher levels of diastolic blood pressure and C‐reactive protein at diagnosis than non‐obese diabetes. Mixed‐effects models indicated the difference in the FPG trajectory before diagnosis by weight status was non‐significant with a slope difference of 0.149 mg/dl (SE = 0.642, p = .816, CHARLS) and 0.013 mg/dl (SE = 0.013, p = .337, ELSA). However, obese diabetes showed a steep increase in HbA1c before diagnosis with a slope difference of 0.036% (SE = 0.016, p = .021) in the CHARLS and 0.032% (SE = 0.014, p = .027) in the ELSA, respectively. Sex‐stratified analyses showed that the difference in HbA1c trajectory before the diabetes diagnosis by weight status was only significant in males.ConclusionsObese and non‐obese diabetes developments may share a similar FPG but distinct HbA1c trajectory. Obese diabetes interventions require more attention to cardiometabolic risks. Moreover, studies addressing weight/sex‐related differences in diabetes aetiologies and treatments are warranted.