Improving patients' knowledge on the relationship between HbA1c and mean plasma glucose improves glycaemic control among persons with poorly controlled diabetes.

BACKGROUND: Recent recommendation advocates the reporting of HbA1c in terms of mean plasma glucose. We examined the impact of improving patients' interpretation of a given HbA1c value on glycaemic control.
METHODS: We conducted a questionnaire survey among 111 patients attending a hospital diabetes clinic. Patients were provided with information relating to the association between HbA1c and mean plasma glucose levels. Glycaemic control among 80 patients with poor glycaemic control was assessed before and approximately seven months after such intervention.
RESULTS: Of the respondents, 40.5% (45/111) were familiar (F) (31 type 1, 14 type 2) and 59.5% (66/111) were unfamiliar (U) (23 type 1, 43 type 2) with the term HbA1c. Following information about the interpretation of HbA1c, patients with poorly controlled diabetes (HbA1c >9%) showed a significant reduction in HbA1c levels if they were from group U (10.7% vs. 9.5%, P = 0.04) but not from group F (10.5 vs. 9.8, P = 0.28). Patients with moderately poor glycaemic control (HbA1c 7.5-9%) showed no significant change in HbA1c levels following intervention (8.3% vs. 8.2%, P = 0.57 group U; 8.3% vs. 8.2%, P = 0.79 group F).
CONCLUSION: Patients' knowledge of HbA1c is poor, especially among persons with type 2 diabetes. Improvement in patients' understanding of HbA1c, particularly among those with very poorly controlled diabetes with no prior knowledge of HbA1c is associated with improvement in their glycaemic control. Strategies to engage patients to know and interpret their HbA1c values should be encouraged within routine clinical practice.