The Mediating Effect of Self-Efficacy on the Relationship Between Medication Literacy and Medication Adherence Among Patients with Type 2 Diabetes

Figures & data

Figure 1 The theoretical framework of this study. (a) Effect of medication literacy on self-efficacy; (b) Effect of self-efficacy on medication adherence; (c) Effect of medication literacy on medication adherence (Without mediation); (c’) Effect of medication literacy on medication adherence (With mediation).

Table 1 Participants Characteristics (n=402)

Factors	Items	N	%
Gender	Male	249	61.9
	Female	153	38.1
Age	18–40	49	12.2
	41–50	60	14.9
	51–60	131	32.6
	61–70	108	26.9
	>70	54	13.4
BMI	<18.5	11	2.7
	18.5–24.9	246	61.2
	25.0–29.9	121	30.1
	30.0–34.9	22	5.5
	≥35.0	2	0.5
Education level	Primary or below	92	22.9
	Junior middle school	97	24.1
	Senior high school or secondary specialized school	94	23.4
	Junior college	48	11.9
	Bachelor degree or above	71	17.7
Marital status	Unmarried	15	3.7
	Married	362	90.0
	Divorced	4	1.0
	Widowed	21	5.2
Residence area	Urban	290	72.1
	Rural	112	27.9
Employment status	Employed	140	34.8
	Part-time job	25	6.2
	Unemployed	108	26.9
	Retired	129	32.1
Medical insurance	Not insured	5	1.2
	New rural cooperative medical insurance	132	32.8
	Basic medical insurance system for urban residents	265	65.9
Annual income	<10,000/year	23	5.7
	10,000–29,999/year	110	27.4
	30,000–49,999/year	157	39.1
	50,000–99,999/year	90	22.4
	≥100,000/year	22	5.5
Smoking	Never smoker	237	59.0
	Current smoker	108	26.9
	Former smoker	57	14.2
Alcohol consumption	Abstinent	317	78.9
	Moderate drinking*	77	19.2
	Heavy drinking	8	2.0
Exercise	No exercise	63	15.7
	Exercise occasionally	100	24.9
	Exercise regularly	239	59.5
Disease duration	<1 year	69	17.2
	1–5 years	86	21.4
	5.1–10 years	86	21.4
	10.1–15 years	74	18.4
	15.1–20 years	59	14.7
	≥20.1 years	28	7.0
Therapy method	Antihyperglycemic drugs + insulin	146	36.3
	Antihyperglycemic drugs	169	42.0
	Insulin	64	15.9
	Without therapy	23	5.7
Number of antihyperglycemic drugs	0	87	21.6
	1	104	25.9
	2	155	38.6
	3	47	11.7
	4	9	2.2
HbA1c	<7.0	68	16.9
	≥7.0	334	83.1
Family history of diabetes	No	214	53.2
	Yes	188	46.8

Notes: *Moderate drinking: Defined as ≤ 100 mL of white wine or a large half glass of red wine or 2 bottles of beer per day for men or ≤ 50 mL of white wine or a small half glass of red wine or 1 bottle of beer per day for women.

Table 2 Medication Literacy, Self-Efficacy, and Medication Adherence Scores of the Participants (n=402)

Factors	Items	Medication Literacy	t/f	p	Self-Efficacy	t/f	p	Medication Adherence	t/f	p
Gender	Male	10.18±2.69	5.569	<0.001	34.08±2.46	2.683	0.008	6.51±1.22	0.440	0.660
	Female	8.24±3.77			33.36±2.88			6.46±1.39
Age	18–40	12.00±1.80	13.828	<0.001	34.10±2.73	0.423	0.792	6.34±1.40	2.498	0.042
	41–50	10.45±2.53			33.70±2.40			6.42±1.06
	51–60	9.15±3.08			33.78±2.46			6.49±1.18
	61–70	8.50±3.68			33.64±3.03			6.36±1.51
	>70	8.59±3.29			34.07±2.52			6.98±1.06
BMI	<18.5	8.73±3.41	0.193	0.942	33.00±2.79	1.394	0.235	6.57±1.34	1.080	0.366
	18.5–24.9	9.49±3.17			33.99±2.31			6.57±1.25
	25.0–29.9	9.37±3.58			33.42±3.32			6.32±1.37
	30.0–34.9	9.68±3.00			34.32±1.64			6.45±1.12
	≥35.0	9.00±1.41			34.00±2.83			7.50±0.71
Education level	Primary or below	5.71±2.99	97.544	<0.001	31.98±3.03	24.092	<0.001	6.22±1.45	2.098	0.080
	Junior middle school	9.03±2.30			33.63±1.71			6.70±1.20
	Senior high school or secondary specialized school	10.31±2.34			34.06±2.02			6.62±1.26
	Junior college	11.71±1.73			34.77±2.44			6.55±0.88
	Bachelor degree or above	12.15±1.71			35.44±2.64			6.36±1.38
Marital status	Unmarried	10.80±2.18	9.080	<0.001	34.93±1.53	1.092	0.353	6.08±1.24	0.978	0.403
	Married	9.58±3.19			33.78±2.71			6.53±1.28
	Divorced	9.50±4.65			33.00±3.65			5.94±1.42
	Widowed	6.05±3.50			33.57±1.96			6.31±1.44
Residence area	Urban	10.21±2.95	8.169	<0.001	34.19±2.45	4.810	<0.001	6.51±1.24	0.441	0.660
	Rural	7.45±3.27			32.81±2.90			6.45±1.39
Employment status	Employed	11.21±2.45	67.788	<0.001	34.31±2.43	18.218	<0.001	6.38±1.23	4.778	0.003
	Part-time job	8.12±2.88			33.16±1.75			6.26±1.31
	Unemployed	6.55±3.09			32.39±2.99			6.29±1.50
	Retired	10.20±2.50			34.58±2.21			6.84±1.07
Medical insurance	Not insured	8.40±4.62	50.285	<0.001	32.60±3.44	21.946	<0.001	6.50±1.08	3.006	0.051
	New rural cooperative medical insurance	7.36±3.34			32.65±2.87			6.27±1.47
	Basic medical insurance system for urban residents	10.49±2.68			34.41±2.31			6.60±1.18
Annual income	<10,000/year	8.52±3.48	16.830	<0.001	32.52±2.92	14.197	<0.001	6.62±1.16	1.239	0.294
	10,000–29,999/year	7.83±3.62			32.76±3.17			6.30±1.39
	30,000–49,999/year	9.51±3.01			33.79±1.98			6.48±1.28
	50,000–99,999/year	11.01±2.34			35.11±2.32			6.70±1.24
	≥100,000/year	11.55±2.13			35.18±2.06			6.52±1.03
Smoking	Never smoker	9.04±3.54	4.885	0.008	33.70±2.86	0.963	0.383	6.54±1.31	1.426	0.241
	Current smoker	10.19±2.53			34.11±2.12			6.32±1.15
	Former smoker	9.68±3.17			33.70±2.67			6.63±1.41
Alcohol consumption	Abstinent	9.19±3.38	4.669	0.010	33.73±2.78	3.096	0.046	6.54±1.28	2.086	0.125
	Moderate drinking	10.45±2.72			34.30±1.95			6.40±1.31
	Heavy drinking	9.50±2.27			32.13±2.23			5.66±1.15
Exercise	No exercise	8.59±3.42	2.547	0.080	32.79±3.69	7.748	<0.001	6.49±1.34	3.171	0.043
	Exercise occasionally	9.62±3.48			33.55±2.58			6.22±1.41
	Exercise regularly	9.59±3.14			34.18±2.25			6.61±1.20
Disease duration	<1 year	10.16±3.31	1.544	0.175	33.96±2.66	1.158	0.329	6.62±1.12	0.465	0.802
	1–5 years	9.66±2.98			33.80±2.28			6.37±1.52
	5.1–10 years	9.00±3.59			33.48±3.30			6.41±1.37
	10.1–15 years	8.99±3.45			34.05±2.43			6.57±1.23
	15.1–20 years	9.71±3.03			34.19±2.16			6.50±1.14
	≥20.1 years	8.96±2.94			33.04±2.90			6.59±1.06
Therapy method	Antihyperglycemic drugs + insulin	9.81±3.23	2.182	0.090	33.77±3.02	1.429	0.234	6.40±1.25	0.983	0.401
	Antihyperglycemic drugs	8.95±3.45			33.79±2.44			6.51±1.38
	Insulin	9.81±2.69			33.56±2.30			6.71±1.03
	Without therapy	9.65±3.59			34.87±2.44			6.37±1.38
Number of antihyperglycemic drugs	0	9.77±2.93	0.630	0.642	33.91±2.39	0.254	0.907	6.62±1.14	0.414	0.799
	1	9.45±3.48			33.59±2.66			6.51±1.34
	2	9.18±3.23			33.86±2.34			6.40±1.30
	3	9.49±3.79			33.94±3.99			6.50±1.44
	4	10.33±2.18			33.89±1.17			6.44±1.01
HbA1c	<7.0	9.32±3.48	−0.322	0.748	33.78±2.34	−0.099	0.921	6.63±1.20	0.937	0.349
	≥7.0	9.46±3.24			33.81±2.71			6.46±1.30
Family history of diabetes	No	9.15±3.46	−1.918	0.056	33.84±2.54	0.226	0.822	6.58±1.27	1.518	0.130
	Yes	9.77±3.03			33.78±2.78			6.39±1.29

Table 3 Descriptive Statistics and Correlations of Medication Literacy, Self-Efficacy, and Medication Adherence (n=402)

	Mean ± SD	Medication Literacy	Self-Efficacy	Medication Adherence
Medication literacy	9.44±3.28	1
Self-efficacy	33.81±2.65	0.499**	1
Medication adherence	6.49±1.28	0.227**	0.392**	1

Note: **p < 0.01.

Table 4 Summary of the Mediating Effects of Self-Efficacy

Variables/Effects	B	SE	t	p	95% CI
Medication literacy - Self-efficacy	0.330	0.048	6.824	<0.001	(0.235, 0.425)
Self-efficacy - Medication adherence	0.188	0.026	7.196	<0.001	(0.137, 0.240)
Medication literacy -Medication adherence	0.169	0.026	6.416	<0.001	(0.117, 0.221)
Effects
Direct effect	0.107	0.026	4.081	<0.001	(0.056, 0.159)
Indirect effect	0.062	0.017			(0.032, 0.100)
Total effect	0.169	0.026	6.416	<0.001	(0.117, 0.221)

Figure 2 The mediating effect of self-efficacy on the relationship between medication literacy and medication adherence. (a) Effect of medication literacy on self-efficacy; (b) Effect of self-efficacy on medication adherence; (c) Effect of medication literacy on medication adherence (Without mediation); (c’) Effect of medication literacy on medication adherence (With mediation).