It was both exciting and disheartening to read about this study.

It was exciting because it was a right research field to expend more effort and investment in so to better elucidate the associations between diabetes self-care activities and its proximal significant factors among the Malaysian adults with type 2 diabetes.
Unfortunately, it was very disheartening to learn about the primary choice of the data collection was by face-to-face interview. It was unclear how the interviews were conducted such as who were the interviewers, when and where was this interview opportunity occurred, the challenges to complete the sensitive items in the DDS-17 and PHQ-9 questionnaires, and the SDSCA and DMSES that are proned to receive socially acceptable responses. These patient-reported data were important to be collected at utmost consideration in the study design that they represent the patients' personal views. This method of measurement might introduce systematic biases into the study that was impossible to be remedied in statistical analysis.
It was also not clear how many language versions of the questionnaires were used in the study. Did all the respondent answer in Malay? In the text, it is mentioned that eligible participants "... can at least understand the Malay language." Were English and Chinese also used by the respondents in their replies or when expressing their views? It was possible that during the initiation of the study, there were true lacking of evidence in the field of emotional distress (inclusive of diabetes distress and depression) among the Malaysian adults with T2D, in particular at the primary care setting of the public health clinics. However, in years 2015 and 2016 there have been some Malaysian studies that were published (even in PLOS One) in the fields of emotional distress in this population that the authors (and the reviewers and editor) seem to miss all of them. I list most of them below, among them are the reliability and validity of the English and Malay versions of the 17-item Diabetes Distress Scale:

1. Chin YW, Lai PS, Chia YC. The validity and reliability of the English version of the diabetes distress scale for type 2 diabetes patients in Malaysia. BMC Fam Pract. 2017 Feb 20;18(1):25. doi: 10.1186/s12875-017-0601-9.
2. Chew BH, Vos R, Mohd-Sidik S, Rutten GE. Diabetes-Related Distress, Depression and Distress-Depression among Adults with Type 2 Diabetes Mellitus in Malaysia. PLoS One. 2016 Mar 22;11(3):e0152095. doi: 10.1371/journal.pone.0152095. eCollection 2016.
3. Chew BH, Mohd-Sidik S, Shariff-Ghazali S. Negative effects of diabetes-related distress on health-related quality of life: an evaluation among the adult patients with type 2 diabetes mellitus in three primary healthcare clinics in Malaysia. Health Qual Life Outcomes. 2015 Nov 24;13:187. doi: 10.1186/s12955-015-0384-4.
4. Chew BH. Medication adherence on quality of life among adults with type 2 diabetes mellitus: an exploratory analysis on the EDDMQoL study. Qual Life Res. 2015 Nov;24(11):2723-31. doi: 10.1007/s11136-015-1006-7. Epub 2015 May 23.
5. Chew BH, Hassan NH, Sherina MS. Determinants of medication adherence among adults with type 2 diabetes mellitus in three Malaysian public health clinics: a cross-sectional study. Patient Prefer Adherence. 2015 May 6;9:639-48. doi: 10.2147/PPA.S81612. eCollection 2015.
6. Chew BH, Sherina MS, Hassan NH. Association of diabetes-related distress, depression, medication adherence, and health-related quality of life with glycated hemoglobin, blood pressure, and lipids in adult patients with type 2 diabetes: a cross-sectional study. Ther Clin Risk Manag. 2015 Apr 29;11:669-81. doi: 10.2147/TCRM.S81623. eCollection 2015.
7. Manan MM, Husin AR, Alkhoshaiban AS, Al-Worafi YM, Ming LC. Interplay between Oral Hypoglycemic Medication Adherence and Quality of Life among Elderly Type 2 Diabetes Mellitus Patients. J Clin Diagn Res. 2014 Dec;8(12):JC05-9. doi: 10.7860/JCDR/2014/10481.5309.
8. Chew BH, Mukhtar F, Sherina MS, Paimin F, Hassan NH, Jamaludin NK. The reliability and validity of the Malay version 17-item Diabetes Distress Scale. Malays Fam Physician. 2015 Aug 31;10(2):22-35.