Exploring the relationship between health knowledge, health literacy, self-care, self-efficacy, and glycemic control among adults with type 2 diabetes mellitus

Table 1 Description and psychometrics of study questionnaires[23-37]

Number	Domain	Description	Psychometrics
1	Sociodemographic and clinical data	24 items, e.g., age, gender, ethnicity, blood pressure, body weight, diabetes complications, etc	Not applicable
2	Laboratory data	8 specific laboratory test results, e.g. fasting glucose, fasting lipids, HbA1c	Not applicable
3	Self-care	There are several versions of Summary of Diabetes Self-care Activities scale. It was developed by Toobert et al[23]. The self-care activities of patients with diabetes included diet, physical activity, blood glucose self-monitoring, foot care, smoking, and medication adherence. The 10-item version (excluding smoking and medication adherence) was validated in Malaysia by Bujang et al[24]. The version used in this study had 11 items (five diet items instead of four)	Cronbach’s α of subscales varied between 0.651 and 0.905 as reported by Bujang et al[24] (based on 10-item version)
4	Self-efficacy	Diabetes Management Self Efficacy Scale-15, a 15-item scale measuring the confidence of respondents in their ability to carry out actions that promote diabetes management. It has been validated in the United Kingdom by Sturt et al[25]. This scale was a shortened version of the original 20-item version developed by Bijl et al[26]	No prior validation had been published from Malaysia
5	Health knowledge	Michigan Diabetes Knowledge Test-14 was developed by Fitzgerald et al[27]. Some versions include another 9 items on insulin use (these were not included in this study). Threshold of adequate diabetes knowledge is a score ≥ 7	Cronbach’s α = 0.702 as reported by Al-Qazaz et al[28]
6	Health literacy	Health literacy is the ability to access, read, understand, and use health information to make appropriate healthcare decisions and follow instructions for treatment. Malaysian version of Health Literacy Survey is a shorter 18-item version developed from the European Health Literacy Survey[29]. Threshold for limited health literacy was set at transformed health literacy score ≤ 33 (hence, sufficient or excellent level is > 33)	Cronbach’s α = 0.906 as reported by Mohamad et al[30]
7	Medication adherence	Malaysia Medication Adherence Assessment Tool is a 12-item scale developed by Hatah et al[31]. Score ≥ 54 was considered as adherence	Cronbach’s α = 0.910 as reported by Hatah et al[31]
8	Diabetes distress	Diabetes Distress Scale is a 17-item scale assessing diabetes-related emotional distress. It was developed by Polonsky et al[32]. A mean item score of ≥ 3 was considered a level of distress worthy of clinical attention. Four subscales can be computed (emotional burden, physician distress, regimen distress, and interpersonal distress)[33]	Cronbach’s α for Malay version is 0.94 as reported by Chew et al[34]. Cronbach’s α for English version is 0.92 as reported by Chin et al[35]
9	Depression	Patient health questionnaire is a 9-item scale (PHQ-9) based on the diagnostic and statistical manual of mental disorders IV that aims to measure the level of depression. It was developed by Kroenke et al[36]. PHQ-9 score ≥ 10 was indicative of moderate levels of depression. Major depression can be diagnosed if the following criteria are satisfied: (1) Item 1 or item 2 scores ≥ 2; and (2) Five items with the following scoring: Items 1-8 scores ≥ 2 or item 9 score ≥ 1	Cronbach’s α = 0.67 as reported by N Azah et al[37]

HbA1c: Glycated hemoglobin.

Table 2 Sociodemographic data of study participants

Variables	Frequency (%)
Age group (n = 100)
< 50	16 (16.0)
50-59	27 (27.0)
≥ 60	57 (57.0)
Gender (n = 100)
Male	51 (51.0)
Female	49 (49.0)
Ethnic group (n = 100)
Malay	20 (20.0)
Chinese	33 (33.0)
Indian	45 (45.0)
Others	2 (2.0)
Education (n = 98)
Less than form 51	54 (55.1)
Form 5 or above	44 (44.9)
Income2 (n = 97)
B40	89 (91.8)
M40 or T20	8 (8.2)

¹Equivalent of year 11 of education.

²Defined based on percentile, B40 represents households in the bottom 40% income bracket, M40 includes those in the 41^st to 80^th percentile, and T20 refers to the top 20% of income earners.

Table 3 Achievement of clinical audit criteria among study participants

Variables	Frequency (%)
Current smoking (n = 100)	13 (13.0)
Central obesity1 (n = 97)	78 (80.4)
Controlled BP2 (n = 100)	38 (38.0)
Good glycemic control3 (n = 99)	43 (43.4)
CKD stage 3 and above4 (n = 100)	15 (15.0)
Optimal LDL-C level5 (n = 97)	41 (42.3)
Urine proteinuria or microalbuminuria (n = 89)	28 (31.5)
Statin use (n = 100)	77 (77.0)

¹Male ≥ 90 cm, female ≥ 80 cm.

²Blood pressure < 140/80 mmHg.

³Glycated hemoglobin ≤ 7.0%.

⁴Epidermal growth factor receptor < 60 mL/minute.

⁵Low-density lipoprotein < 2.6 mmol/L.

CKD: Chronic kidney disease; LDL-C: Low-density lipoprotein cholesterol.

Table 4 Statistical data of key variables

	Measurement or questionnaire	Cronbach’s α	mean ± SD (range)	Number (%) at specific threshold1	Association with sociodemographic data, mean ± SD
Diabetes knowledge (n = 99)	MDKT-14	0.564	7.3 ± 2.5 (1-13)	Adequate knowledge: 59 (59.6)	Higher MDKT score among patients with education at form 5 or above: 8.3 (2.4) vs 6.5 (2.4), P < 0.001
Health literacy (n = 96)	HLS-M-Q18	0.904	True score: 54.9 ± 9.7 (26.0-71.0); Transformed score: 38.1 ± 6.7 (18.1-49.3)	Sufficient/excellent health literacy: 77 (80.2)	Lower HLS score among Chinese patients compared with other ethnic groups: 51.5 (10.5) vs 56.4 (8.9), P = 0.021
Self-efficacy (n = 100)	DMSES-15	0.878	110.6 ± 26.0 (30-150)	Not applicable	No association with sociodemographic data
Self-care (n = 98)	SDSCA-11	0.601	30.7 ± 13.3 (7-64)	Not applicable	Higher SDSCA score among patients with education at form 5 or above: 33.6 (14.3) vs 28.1 (11.4), P = 0.045
Medication adherence (n = 100)	MyMAAT-12	0.909	50.8 ± 9.3 (15-60)	Adherent: 51 (51.0)	MyMAAT score higher in those aged ≥ 60 vs those aged < 60: 52.6 (8.6) vs 48.5 (9.8), P = 0.027

¹See Table 1. MDKT-14: Michigan Diabetes Knowledge Test-14; HLS-M-Q18: Malaysian version of Health Literacy Survey Questionnaire 18; DMSES-15: Diabetes Management Self Efficacy scale-15; SDSCA-11: Summary of Diabetes Self-Care Activities-11; MyMAAT-12: Malaysia Medication Adherence Assessment Tool-12; SD: Standard deviation.

Table 5 Correlation among self-care, diabetes knowledge, glycemic control, health literacy, self-efficacy, and medication adherence

	Diabetes knowledge	Glycemic control	Health literacy	Self-efficacy	Medication adherence
Self-care	0.16 (0.128)	0.06 (0.565)	0.31 (0.003)	0.49 (< 0.001)	0.37 (< 0.001)
Self-care (diet subscale)	0.07 (0.494)	-0.03 (0.736)	0.15 (0.135)	0.32 (0.001)	0.41 (< 0.001)
Diabetes knowledge		0.07 (0.495)	0.31 (0.002)	0.21 (0.038)	0.02 (0.827)
Glycemic control			-0.16 (0.125)	-0.01 (0.898)	0.09 (0.376)
Health literacy				0.55 (< 0.001)	0.13 (0.197)
Self-efficacy					0.11 (0.286)

The result was presented using correlation coefficient (P value).