Evidence check: HbA1c in the context of fertility

HbA1c is a long-term marker of glycemic control. Elevated levels (>5.7% or >39 mmol/mol) indicate impaired glucose tolerance or diabetes. In fertility medicine, there is evidence that poor glycemic control—especially in women with PCOS or obesity—can negatively affect egg quality, ovulation, and implantation rates. In men, elevated HbA1c has been linked to reduced sperm quality. However, the evidence is moderate: most studies are observational, and effects are often confounded by age, BMI, and hormonal status. A normal HbA1c does not guarantee fertility, nor does an elevated value exclude it. The test should be interpreted clinically. Caveat: HbA1c is not a direct fertility marker but a risk indicator. The provided context does not contain specific studies on HbA1c and fertility; this answer is based on general medical knowledge.