An HbA1c of 6.8% indicates your levels are slightly in the diabetic range, so using a sugar-free herbal cough syrup is a safe choice. The standard recommended dosage for adults is 1 to 2 teaspoons (5 to 10 ml) three to four times daily. You can safely take this for 3 to 5 days to relieve your symptoms. If your cough, cold, or blocked nose persists beyond a week or if you develop a fever, please consult your doctor. Also, monitor your blood sugar, as minor infections can sometimes cause mild fluctuations.