Objective: Few prospective studies have assessed whether persons with subclinical thyroid dysfunction are more likely to develop diabetes, with conflicting results. We conducted a systematic review of the literature and an individual participant data analysis of multiple prospective cohorts to investigate the association between subclinical thyroid dysfunction and incident diabetes. Methods: We performed a systematic review of the literature in Medline, Embase, and the Cochrane Library from inception to February 11 2022. A two-stage individual participant data analysis was conducted to compare participants with subclinical hypothyroidism and subclinical hyperthyroidism versus euthyroidism at baseline and the adjusted risk of developing diabetes at follow-up. Results: Among 61,178 adults from 18 studies, mean age was 58 years, 49% were females, and mean follow-up time was 8.2 years. At last available follow-up, there was no association between subclinical hypothyroidism and incidence of diabetes (OR=1.02, 95% confidence interval (CI): 0.88-1.17, I2=0%), or subclinical hyperthyroidism and incidence of diabetes (OR=1.03, 95% CI: 0.82-1.30, I2=0%), in age- and sex-adjusted analyses. Time-to-event analysis showed similar results (hazard ratio for subclinical hypothyroidism: 0.98, 95% CI: 0.87-1.11; hazard ratio for subclinical hyperthyroidism: 1.07, 95% CI: 0.88-1.29). The results were robust in all subgroup and sensitivity analyses. Conclusions: This is the largest systematic review and individual participant data analysis to date investigating the prospective association between subclinical thyroid dysfunction and diabetes. We did not find an association between subclinical thyroid dysfunction and incident diabetes. Our results do not support screening patients with subclinical thyroid dysfunction for diabetes.

BackgroundIn multimorbid older patients with type 2 diabetes mellitus (T2DM), the intensity of glucose‐lowering medication (GLM) should be focused on attaining a suitable level of glycated hemoglobin (HbA1c) while avoiding side effects. We aimed at identifying patients with overtreatment of T2DM as well as associated risk factors.MethodsIn a secondary analysis of a multicenter study of multimorbid older patients, we evaluated HbA1c levels among patients with T2DM. Patients were aged ≥70 years, with multimorbidity (≥3 chronic diagnoses) and polypharmacy (≥5 chronic medications), enrolled in four university medical centers across Europe (Belgium, Ireland, Netherlands, and Switzerland). We defined overtreatment as HbA1c < 7.5% with ≥1 GLM other than metformin, as suggested by Choosing Wisely and used prevalence ratios (PRs) to evaluate risk factors of overtreatment in age‐ and sex‐adjusted analyses.ResultsAmong the 564 patients with T2DM (median age 78 years, 39% women), mean ± standard deviation HbA1c was 7.2 ± 1.2%. Metformin (prevalence 51%) was the most frequently prescribed GLM and 199 (35%) patients were overtreated. The presence of severe renal impairment (PR 1.36, 1.21–1.53) and outpatient physician (other than general practitioner [GP], i.e. specialist) or emergency department visits (PR 1.22, 1.03–1.46 for 1–2 visits, and PR 1.35, 1.19–1.54 for ≥3 visits versus no visits) were associated with overtreatment. These factors remained associated with overtreatment in multivariable analyses.ConclusionsIn this multicountry study of multimorbid older patients with T2DM, more than one third were overtreated, highlighting the high prevalence of this problem. Careful balancing of benefits and risks in the choice of GLM may improve patient care, especially in the context of comorbidities such as severe renal impairment, and frequent non‐GP healthcare contacts.

Introduction Older and multimorbid adults with type 2 diabetes (T2D) are at high risk of cardiovascular disease (CVD) and chronic kidney disease (CKD). Estimating risk and preventing CVD is a challenge in this population notably because it is underrepresented in clinical trials. Our study aims to (1) assess if T2D and haemoglobin A1c (HbA1c) are associated with the risk of CVD events and mortality in older adults, (2) develop a risk score for CVD events and mortality for older adults with T2D, (3) evaluate the comparative efficacy and safety of novel antidiabetics. Methods and analysis For Aim 1, we will analyse individual participant data on individuals aged ≥65 years from five cohort studies: the Optimising Therapy to Prevent Avoidable Hospital Admissions in Multimorbid Older People study; the Cohorte Lausannoise study; the Health, Aging and Body Composition study; the Health and Retirement Study; and the Survey of Health, Ageing and Retirement in Europe. We will fit flexible parametric survival models (FPSM) to assess the association of T2D and HbA1c with CVD events and mortality. For Aim 2, we will use data on individuals aged ≥65 years with T2D from the same cohorts to develop risk prediction models for CVD events and mortality using FPSM. We will assess model performance, perform internal-external cross validation, and derive a point-based risk score. For Aim 3, we will systematically search randomized controlled trials of novel antidiabetics. Network meta-analysis will be used to determine comparative efficacy in terms of CVD, CKD, and retinopathy outcomes, and safety of these drugs. Confidence in results will be judged using the CINeMA tool. Ethics and dissemination Aims 1 and 2 were approved by the local ethics committee (Kantonale Ethikkommission Bern); no approval is required for Aim 3. Results will be published in peer-reviewed journals and presented in scientific conferences.