A 45-year-old man attends a health assessment. He has a sedentary occupation, a waist circumference of 108 cm and a first-degree relative with type 2 diabetes, but no polyuria or weight loss. His AUSDRISK score is 14, and a venous HbA1c is 6.2% (44 mmol/mol; diabetes diagnostic threshold at least 6.5%, 48 mmol/mol). Which one of the following is the most appropriate interval for repeat diabetes testing?