Laboratory parameters
We measured serum thyroid stimulating hormone (TSH), free trijodothyronine (fT3), free thyroxine (fT4) and glycated hemoglobin (HbA1c) in all trial participants. Laboratory analyses were conducted at the central lab of the University Hospital Basel. TSH and fT3/fT4 were measured with electro-chemiluminescence immunoassays (Elecsys, all assays from Roche Diagnostics GmbH, Mannheim, Germany). The reference ranges were as follows: TSH, 0.332–4.490 mIU/l, free T3: 2.6-5.6 pmol/l and free T4 11.6-22.0 pmol/l. HbA1c was measured at the point of care (DCA Vantage, Siemens Healthineers, Erlangen, Germany).