We investigated whether patients' perceived glycemic control and self-reported diabetes self-care correlated with their actual glycemic control.

A survey was administered among patients with diabetes mellitus at an outpatient clinic with structured self-report questionnaires regarding perceived glycemic control and diabetes self-management. Actual glycemic control was defined as a change in glycated hemoglobin (A1C) or fasting plasma glucose (FPG) since the last clinic visit.

Patients who perceived their glycemic control as "improved" actually showed a mild but significant decrease in the mean A1C (-0.1%, P=0.02), and those who perceived glycemic control as "aggravated" had a significant increase in the mean FPG (10.5 mg/dL or 0.59 mmol/L, P=0.04) compared to the "stationary" group. However, one-half of patients falsely predicted their actual glycemic control status. Subjective assessment of diabetes self-care efforts, such as adherence to a diet regimen or physical activity, correlated positively with perceived glycemic control but showed no association with actual glycemic control.

Patients should be encouraged to assess and monitor diabetes self-care more objectively to motivate behavioral modifications and improve their actual glycemic control.