Abstract / Summary
Background: Accurate scoring is essential when patient-reported self-management instruments are related to biochemical outcomes. The principal contribution of this study was to reconstruct and audit Diabetes Self-Management Questionnaire (DSMQ) scores from item-level data before reassessing their cross-sectional association with glycemic control. Methods: We performed a cross-sectional secondary analysis of a clinical database of adults with type 2 diabetes. One non-patient header row was removed. Because 12 observation-sheet identifiers occurred twice and visit dates were unavailable, all 24 records carrying repeated identifiers were excluded from the prespecified primary analysis, leaving 238 records. Negatively keyed DSMQ items were reverse-scored, and total and subscale scores were transformed to a 0–10 scale according to the original algorithm. Associations with HbA1c were assessed using Spearman correlation, exploratory ROC analysis, and multivariable linear regression with HC3 robust standard errors. Results: HbA1c was available for 237 records; mean age was 64.18 years (SD 11.14), 56.1% of records with valid sex coding were female, and mean HbA1c was 7.81% (SD 1.94). The corrected DSMQ total score was 5.19 (SD 2.36). DSMQ total score correlated inversely with HbA1c (ρ = −0.467, bootstrap 95% CI −0.572 to −0.350; p < 0.001). In the adjusted model (n = 236), each one-point higher DSMQ total score was associated with a 0.254 percentage-point lower HbA1c (regression coefficient = −0.254, 95% CI −0.344 to −0.163; p < 0.001). Sensitivity analyses using all records or first/last repeated-record rules produced similar estimates. Conclusions: Correctly scored DSMQ results showed a moderate, independent cross-sectional association with HbA1c. The corrected analysis did not demonstrate excellent discrimination, and the cross-sectional data cannot support causal or predictive claims. Prospective studies with verified unique participants and clearly documented data provenance are needed.