A 46-year-old woman has a body mass index of 32 kg/m² and treated hypertension. Her mother developed type 2 diabetes at 58 years of age. She has no polyuria, polydipsia or weight loss; her blood pressure is controlled and her HbA1c is 5.5% (37 mmol/mol; reference range less than 42 mmol/mol). She has not previously been diagnosed with diabetes or prediabetes. She asks when blood testing should be repeated, as she is trying to reduce her weight. Which one of the following is the most appropriate interval?