Validation of Diabetes Knowledge Questionnaire (DKQ) in the Taiwanese Population — Concurrent Validity with Diabetes-Specific Quality of Life Questionnaire Module

Figures & data

Table 1 Demographic Characteristics

	Entire Sample (n=425)		Pre- and Post-Test Sample (n=51)		Test–Retest Sample (n=77)
	n	%	n	%	n	%
Gender
Female	197	46.35%	19	37.25%	34	44.16%
Male	228	53.65%	32	62.75%	43	55.84%
Age (years)^a	58.4±11.6		60.47±11.48		57.52±11.92
≤50	94	22.12%	8	15.69%	21	27.27%
50<Age≤60	190	44.71%	26	50.98%	33	42.86%
>60	141	33.18%	17	33.33%	23	29.87%
Education
≤Junior high school	104	24.47%	19	37.25%	14	18.18%
Senior high school	154	36.24%	15	29.41%	34	44.16%
≥College	167	39.29%	17	33.33%	29	37.66%
DM duration (yr)^a	8.9±7.2		4.98±6.72		9.75±7.5
≤4	145	34.12%	29	56.86%	24	31.17%
4< duration ≤11	142	33.41%	14	27.45%	26	33.77%
>11	138	32.47%	8	15.69%	27	35.06%
HbA1c (%)^a	7.4±1.3		8.54±2.06		7.25±1.02
≤7	195	45.88%	15	29.41%	39	50.65%
7<HbA1c≤8.5	157	36.94%	13	25.49%	28	36.36%
>8.5	73	17.18%	23	45.10%	10	12.99%
Diabetes treatment
Diet only	21	4.94%	3	5.88%	3	3.9%
Oral antidiabetic agents (OAD)	331	77.88%	42	82.35%	55	71.43%
Insulin, GLP-1 agonists or both	7	1.65%	0	0%	2	2.6%
OAD and injection therapy	66	15.53%	6	11.76%	17	22.08%

Note: ^aReported using mean±sd.

Table 2 Rotated Factor Matrix of Exploratory Factor Analysis

DKQ Item*	Factor
	F1: Diabetes Etiology and Symptom	F2: Intermediate Nursing	F3: Complications	F4: Diet and Treatment	F5: Elementary Nursing	Retained or Deleted
4. Kidneys produce insulin.	0.709					Retained
3. Diabetes is caused by failure of the kidneys to keep sugar out of the urine.	0.647	−0.112		−0.155		Retained
22. Frequent urination and thirst are signs of low blood sugar.	0.497	0.104				Retained
21. Shaking and sweating are signs of high blood sugar.	0.398	0.257	−0.222	0.105	0.128	Retained
12. An insulin reaction is caused by too much food.	0.360					Retained
9. The best way to check my diabetes is by testing my urine.	0.336	0.159				Retained
7. Diabetes can be cured.	0.249			0.128		Deleted
10. Regular exercise will increase the need for insulin or other diabetic medication.	0.214	0.196	0.164		−0.124	Deleted
17. A person with diabetes should cleanse a cut with iodine and alcohol.	−0.159	0.642	−0.117		0.204	Retained
24. A diabetic diet consists mostly of special foods.	0.161	0.457				Retained
23. Tight elastic hose or socks are not bad for diabetics.		0.450	0.141	0.103		Retained
13. Medication is more important than diet and exercise to control my diabetes.	0.123	0.263	0.233		−0.143	Retained
1. Eating too much sugar and other sweet foods is a cause of diabetes.		0.200				Deleted
6. If I am diabetic, my children have a higher chance of being diabetic.	0.171	−0.190	0.118	0.175		Deleted
20. Diabetes can cause loss of feeling in my hands, fingers, and feet.	0.120		0.639			Retained
19. Diabetes can damage my kidneys.	−0.176		0.495		0.201	Retained
14. Diabetes often causes poor circulation.	−0.133		0.436			Retained
5. In untreated diabetes, the amount of sugar in the blood usually increases.				0.678		Retained
18. The way I prepare my food is as important as the foods I eat.				0.479	−0.115	Retained
2. The usual cause of diabetes is lack of effective insulin in the body.	0.107	−0.154		0.285	0.232	Deleted
11. There are two main types of diabetes: type 1 (insulin-dependent) and type 2 (non-insulin dependent).	0.194			0.212		Deleted
8. A fasting blood sugar level of 210 is too high.					0.417	Retained
16. Diabetics should take extra care when cutting their toenails.		0.148	0.182		0.415	Retained
15. Cuts and abrasions on diabetics heal more slowly.			0.279		0.314	Retained

Notes: Factor loadings >0.3 are presented in bold; in each factor column, the factor loading of each corresponding item is presented in bold. The items with gray background were deleted from DKQ-24. The rest of the items were retained in DKQ-18. The item descriptions in the Table were all identical to those in the original DKQ-24; however, it is strongly recommended replacing “diabetics” to other person-first language (eg, people living with diabetes) with permission from the original authors for future studies which want to use DKQ-24 or DKQ-18. *DKQ items reproduced with permission from: Garcia AA, Villagomez ET, Brown SA, Kouzekanani K, Hanis CL. The Starr County Diabetes Education Study: development of the Spanish-language diabetes knowledge questionnaire. Diabetes Care. 2001;24(1):16–21. Erratum in: Diabetes Care. 2001;24(5):972. doi:10.2337/diacare.24.1.16.²² Copyright © 2001, American Diabetes Association. Copyright and all rights reserved. Material from this publication has been used with the permission of American Diabetes Association.

Table 3 Item Difficulty and Item Discrimination of Each Item in DKQ-18 (N=425)

Factor	Item	Correct Responses	Item Difficulty Index	Discrimination Coefficients
F1: Diabetes etiology and symptoms	4	171	0.402	0.540**
	3	134	0.315	0.456**
	22	240	0.565	0.578**
	21	219	0.515	0.565**
	9	315	0.741	0.529**
	12	165	0.388	0.447**
F2: Intermediate nursing	17	121	0.285	0.375**
	24	293	0.689	0.563**
	23	291	0.685	0.569**
	13	355	0.835	0.444**
F3: Complications	20	395	0.929	0.410**
	19	392	0.922	0.253**
	14	373	0.878	0.325**
F4: Diet and treatment	5	382	0.899	0.366**
	18	407	0.958	0.277**
F5: Elementary nursing	16	405	0.953	0.267**
	8	404	0.951	0.212**
	15	422	0.993	0.199**

Note: **Correlation is significant at the 0.01 level (2-tailed).

Table 4 Concurrent Validity of the DKQ-18 (18 Items Diabetes Knowledge Questionnaire) with the Diabetes Mellitus Quality of Life (DMQoL) Score

Stratification: Educational Level		DKQ-18	Factor 1	Factor 2 Intermediate Nursing	Factor 3	Factor 4 Diet and Treatment	Factor 5 Elementary Nursing
≤ Junior high school (n=104)	r with DMQoL	0.269**	0.129	0.190	0.160	0.201*	0.288**
	P value	0.006	0.191	0.053	0.104	0.041	0.003
Senior high school (n=154)	r with DMQoL	0.056	0.057	−0.026	−0.063	0.200*	0.170*
	P value	0.489	0.483	0.746	0.438	0.013	0.035
≥ College (n=167)	r with DMQoL	0.161*	0.061	0.210**	0.105	0.065	0.087
	P value	0.037	0.434	0.007	0.176	0.402	0.265

Notes: * p < 0.05; ** p < 0.01; The decimals of significant concurrent validity are presented in bold with gray background, either p < 0.05 or p < 0.01.

Table 5 Known-Group Validity of DKQ-18

Variable	n	Mean Score	Std	t/F value^c	p-value	Post-Hoc^d
Gender^a
Female	197	13.28	2.481	−2.560	0.011
Male	228	12.57	3.224
Education^b
①≤Junior high school	104	11.70	2.992	16.705	<0.001	①<②
② Senior high school	154	12.82	2.724			①<③
③≥College	167	13.73	2.795			②<③
HbA1c^b
①≤7	195	13.35	2.664	6.226	0.002	①>③
②7<HbA1c≤8.5	157	12.77	2.961
③>8.5	73	11.99	3.272

Notes: ^aGender by t-test; ^bEducation and HbA1c by ANOVA; ^ct/F value, where t stands for t value and F stands for F value; ^dPost-hoc test: Scheffe for education; Dunnett for HbA1c.

Table 6 Hierarchical Regression Analysis for Variables Predicting Diabetes Knowledge (n=425)

	Model 1			Model 2
	β	t	p	β	t	p
Gender (ref. female)	−0.14	−2.90	0.004	−0.12	−2.59	0.01
Age (years)	0.04	0.88	0.38	0.04	0.70	0.48
BMI	−0.03	−0.57	0.57	−0.01	−0.22	0.83
Education
≤Junior high school	ref.			ref.
Senior high school	0.20	3.25	0.001	0.20	3.30	0.001
≥College	0.36	5.72	< 0.0001	0.37	5.93	<0.0001
DM duration				0.17	3.38	0.001
HbA1c				−0.15	−3.26	0.001
Diabetes treatment
Diet only				ref.
Oral antidiabetic agents (OAD)				−0.04	−0.51	0.61
Insulin, GLP-1 agonists or both				−0.08	−1.60	0.11
OAD and injection therapy				−0.02	−0.24	0.81
	R^2=0.084	F=8.767		R^2=0.133	F=7.492
P	p<0.0001			p<0.0001
ΔR^2			0.059
ΔF			5.723
P for ΔF			p<0.0001

Table 7 t-Test and ANOVA of Six Items Deleted from DKQ-24

	Gender	Education	HbA1c	DM Duration
Item 2	–	① vs ②, p=0.035	–	–
Item 6	–	–	–	–
Item 10	–	–	① vs ②, p=0.04	–
Item 11	–	② vs ③, p=0.002	–	–
Item 1	p=0.023	–	–	–
Item 7	–	–	–	–

Notes: Education level: ①≤ Junior high school; ②=Senior high school; ③≥ College. HbA1c level: ①denotes≤7%; HbA1c ②=7%<HbA1c≤8.5%; HbA1c③>8.5%. DM duration (yr): ①≤4; ②= 4 < duration≤11; ③>11.

Garcia AA, Villagomez ET, Brown SA, Kouzekanani K, Hanis CL. The Starr county diabetes education study: development of the Spanish-language diabetes knowledge questionnaire. Diabetes Care. 2001;24(1):16–21. doi:10.2337/diacare.24.1.16

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