Strengths and Limitations
The study’s strengths include the strong theory base of the intervention informed by an initial pilot study (see Blinded for review) and the mapping of these identified constructs on the intervention content. Further, this study provided one of the first theory-based interventions tackling the fundamental diabetes management behaviour of carbohydrate counting. It offered a test of the utility of the integrated theoretical model in informing health behaviour change in a cultural context where there is a dearth of theory-based health behaviour change interventions for T2D adults. Additional strengths were RCT design and the use of face-to-face interviews by trained health care providers allowing participants to check their understanding of the questions posed, likely improving the reliability of responses.
The relatively small sample size and lack of objective measurements of HbA1c and fasting blood sugar (FBS) is a limitation of the current study. FBS and HbA1c are common outcome measures in diabetes. FBS fluctuates in a short period, and regular test are required for judgment purposes. With respect to limited resources and participants’ possibility of nonattendance for regular visits, we did not measure blood sugar. However, HbA1c changes are measurable after three months. Our post-intervention measurements were performed two months following the latest intervention session, due to time restrictions. Thus, we thought that two months might not accurately demonstrate the effects of TPB intervention on HbA1c.
Our post-intervention measurements were scheduled to be only performed on one occasion, two months post-intervention. Besides, study participants were all IDS members. These individuals are usually highly motivated about their diabetes management, bringing into question the generalizability of the findings to other adults diagnosed with T2D not aligned with a national diabetes organization.