Six-minute walk test in non-insulin-dependent diabetes mellitus patients living in Northwest Africa

Figures & data

Table 1 Clinical, anthropometric, and metabolic characteristics of the non-insulin-dependent diabetes mellitus patient group

	Females (n = 45)	Males (n = 55)	Total sample (n = 100)
Smoking status, medical, surgical and obstetric history, current medication (n)
Cigarette use	1	37**	38
Narghile use	0	8**	8
Chronic respiratory diseases	3	7	10
Arterial hypertension	20	17	37
Dyslipidemia	8	6	14
Cardiovascular diseases	3	4	7
Dysthyroid	4	0**	4
Diabetic retinopathy	3	5	8
Renal failure	0	1	1
Anemia	2	1	3
Surgical history	17	8**	25
Low parity	34
Beta-blocker use	6	4	10
Diuretic use	3	1	4
Bronchodilator use	2	0	2
Socioeconomic, schooling, and physical activity levels (n)
Low socioeconomic level	27	9**	36
Low schooling level	22	15**	37
Sedentary status	32	18**	50
Daily, sporting, leisure, and physical activity scores, parity [median (1st–3rd quartile)]
Activities
Daily	2 (2–2)	1 (1–2)*	2 (1–2)
Sporting	2 (0–7)	8 (3–13)*	6 (1–11)
Leisure	1 (1–2)	2 (1–4)*	2 (1–3)
Physical	6 (4–11)	13 (7–18)*	9 (5–15)
Parity (numerical)	3 (2–4)
Anthropometric data (mean ± SD)
Age (years)	55 ± 8	54 ± 8	54 ± 8
Weight (kg)	80 ± 16	82 ± 11	81 ± 14
Height (m)	1.56 ± 0.06	1.70 ± 0.06*	1.64 ± 0.09
Body mass index (kg/m^2)	33 ± 6	28 ± 4*	30 ± 5
Metabolic data and absolute cardiovascular disease risk (ACVDR) score (mean ± SD)
Fasting glycemia (mmol/L)	9.50 ± 3.24	9.47 ± 2.72	9.49 ± 2.95
Glycated hemoglobin (%)	8 ± 2	8 ± 2	8 ± 2
Triglycerides (mmol/L)	1.47 ± 0.78	1.86 ± 1.50	1.68 ± 1.24
Total cholesterol (mmol/L)	5.04 ± 1.01	4.78 ± 0.78	4.90 ± 0.89
HDL-C (mmol/L)	1.08 ± 0.30	1.06 ± 0.32	1.07 ± 0.31
LDL-C (mmol/L)	3.27 ± 0.92	2.87 ± 0.73*	3.05 ± 0.85
ACVDR score	2 ± 1	4 ± 1*	3 ± 1
Normal weight, overweight, and obese (number)
Normal weight	5	9	14
Overweight	9	29**	38
Obese
Moderate	16	15	31
Marked	10	2**	12
Extreme	5	0**	5
Three degrees of obesity	31	17**	48
Metabolic characteristics (number)
Uncontrolled diabetes	25	33	58
“Measured” dyslipidemia	30	37	67

Notes:

* P (probability, t-test) < 0.05, females vs males;

** P (probability, chi-squared test) < 0.05, females vs males.

Abbreviations: HDL-C, high-density-lipid cholesterol; LDL-C, low-density-lipid cholesterol.

Table 2 Six-minute walk test (6MWT) data of the non-insulin-dependent diabetes mellitus patient group

	Females (n = 45)		Males (n = 55)		Total sample (n = 100)
	Rest	End	Rest	End	Rest	End
Heart rate
(bpm)	81 ± 12	118 ± 19#	78 ± 13	113 ± 20#	79 ± 13	115 ± 19#
(%)	47 ± 7	69 ± 10#	46 ± 8	67 ± 12#	46 ± 7	68 ± 11#
6MWD
(m)	513 ± 63		609 ± 67*		566 ± 81
(%)	98 ± 11		84 ± 9*,†		90 ± 12†
Oxy-sat (%)	98 (97–98)	98 (97–98)	98 (98–98)	98 (97–98)#	98 (97–98)	98 (97–98)
Systolic pressure (mmHg)	130 (120–140)	150 (140–160)#	130 (120–140)	150 (130–160)#	130 (120–140)	150 (140–160)#
Diastolic pressure (mmHg)	80 (80–80)	80 (80–90)#	80 (70–80)	80 (80–90)#	80 (75–80)	80 (80–90)#
Dyspnea (VAS)	0 (0–0)	2 (1–4)#	0 (0–0)	2 (0–3)#	0 (0–0)	2 (1–3)#

Notes:

* P (probability, t-test) < 0.05, females vs males;

# P (probability, t-test) < 0.05, “rest vs end” 6MWT;

† P (probability, t-test) < 0.05, “measured vs theoretical” 6MWD; data are means for heart rate and 6MWD and medians (1st–3rd quartiles) for others.

Abbreviations: 6MWD, 6-minute walk distance; VAS, visual analog scale; bpm, beats per minute; oxy-sat, oxyhemoglobin saturation.

Table 3 Independent variables included in the forward linear stepwise multiple regression model for the 6-minute walk distance (6MWD) of the non-insulin-dependent diabetes mellitus patient group

Independent variables	B	95% CI	Cumulative r ^2
Females (n = 45)
Constant	714.54	630.01–799.07
Age (years)	−3.51	−5.12 to −1.90	0.297
Socioeconomic level (0, low; 1, high)	29.44	2.79–56.09	0.382
Parity (numerical)	−6.09	−12.85–0.67	0.413
Males (n = 55)
Constant	−234.62	−1307.93–838.69
Systolic pressurerest (mmHg)	−0.90	−2.03–0.24	0.091
Leisure activity score	8.88	3.40–14.36	0.166
Cigarette use* (0, no; 1, yes)	−38.35	−65.73 to −10.98	0.234
Oxy-satrest (%)	10.90	0.24–1.56	0.292
Physical activity score	−1.80	−3.89–0.28	0.317
Age (years)	−1.57	−3.39–0.26	0.344
Total sample (n = 100)
Constant	−105.48	−973.64–762.69
Gender (0, male; 1, female)	−73.94	−101.23 to −46.65	0.350
Age (years)	−3.25	−4.43 to −2.07	0.446
Leisure activity score	7.33	3.22–11.45	0.485
Obesity** (0, no; 1, yes)	−35.57	−55.35 to −15.79	0.528
Socioeconomic level (0, low; 1, high)	32.86	11.84–53.87	0.554
Cigarette use* (0, no; 1, yes)	−27.67	−52.49 to −2.86	0.568
Oxy-satrest (%)	8.89	0.17–17.61	0.580

Notes: 95% CI, 95% confidence interval around each B;

* cigarette use: 0, no (use ≤ 2 pack-years); 1, yes (use > 2 pack-years);

** obesity: 0, no (BMI < 30 kg/m²); 1, yes (BMI ≥ 30 kgm²); proposed model for the NIDDM total sample: 6MWD (m) = −73.94 × gender (0, male, 1, female) − 3.25 × age (years) + 7.33 × leisure-activity score − 35.57 × obesity (0, no; 1, yes) + 32.86 × socioeconomic level (0, low; 1, high) − 27.67 × cigarette use (0, no; 1, yes) + 8.89 × oxy-sat_rest − 105.48.

Abbreviation: oxy-sat, oxyhemoglobin saturation.

Table 4 Characteristics of non-insulin-dependent diabetes mellitus patients, divided according to their 6MWD (Group 1, abnormal 6MWD; Group 2: normal 6MWD)

	Group 1 (n = 23)	Group 2 (n = 77)
Smoking, physical activity and absolute cardiovascular disease risk (ACVDR) scores, anthropometric, metabolic and resting 6MWT data (mean ± SD)
Cigarette use (pack-years)	21 ± 13	19 ± 14
Narghile use (narghile-years)	26 ± 49	20 ± 28
Age (years)	51 ± 6	55 ± 8*
Weight (kg)	84 ± 12	80 ± 14
Height (m)	1.69 ± 0.06	1.63 ± 0.09*
Body mass index (kg/m^2)	30 ± 4	30 ± 5
Glycated hemoglobin (%)	7.75 ± 2.16	7.88 ± 2.12
Fasting glycemia (mmol/L)	9.69 ± 3.00	9.42 ± 2.95
Triglycerides (mmol/L)	2.00 ± 1.30	1.59 ± 1.21
Total cholesterol (mmol/L)	4.70 ± 0.73	4.96 ± 0.93
HDL-C (mmol/L)	0.97 ± 0.20	1.10 ± 0.33
LDL-C (mmol/L)	2.81 ± 0.83	3.12 ± 0.84
Physical activity score	13 ± 7	10 ± 6
ACVDR score	4 ± 1	3 ± 1*
Dyspnea (VAS)	0 ± 0	0 ± 0
Heart rate (%)	46 ± 8	47 ± 7
Systolic pressure (mmHg)	129 ± 9	130 ± 14
Diastolic pressure (mmHg)	80 ± 6	79 ± 8
Oxy-sat (%)	98 ± 1	98 ± 1
6MWD
(m)	544 ± 55	573 ± 86
(%)	76 ± 5	94 ± 10*
Percentage of patients with the following characteristics
Cigarette use	83%	25%**
Narghile use	17%	5%
Chronic respiratory diseases	4%	12%
Arterial hypertension	30%	39%
Cardiovascular diseases	13%	5%
Diabetic retinopathy	7%	8%
Surgical history	17%	27%
Beta-blocker use	0%	13%
Low socioeconomic level	30%	38%
Low schooling level	30%	39%
Sedentary status	35%	55%
Obesity	48%	48%
Uncontrolled diabetes	57%	58%
Dyslipidemia history	17%	13%
“Measured” dyslipidemia	87%	61%**

Notes:

* P (probability, t-test) < 0.05;

** P (probability, chi-squared test) < 0.05.

Abbreviations: 6MWD, 6-minute walk distance; 6MWT, 6-minute walk test; HDL, high-density lipoprotein; LDL, low-density lipoprotein; VAS, visual analog scale; oxy-sat, oxyhemoglobin saturation.

Table 5 Comparison of patient group (PG) data with those of three control groups (CG): CG1 (healthy nonobese and nonsmoking); CG2 (nondiabetic obese free from comorbidities); and CG3 (“all comers” – nondiabetics)

	Females				Males				Total sample
	PG (n = 45)	CG1 (n = 87)	CG2 (n = 38)	CG3 (n = 22)	PG (n = 55)	CG1 (n = 87)	CG2 (n = 17)	CG3 (n = 37)	PG (n = 100)	CG1 (n = 174)	CG2 (n = 55)	CG3 (n = 59)
Data are means ± standard deviation
Cigarette use (PY)	2 ± 1δ	0 ± 0*	0 ± 0†	0 ± 0#	21 ± 13	0 ± 0*	0 ± 0†	20 ± 22	20 ± 13	0 ± 0*	0 ± 0†	13 ± 20
Narghile use (NY)	0 ± 0	0 ± 0	0 ± 0	0 ± 0	23 ± 38δ	0 ± 0*	0 ± 0†	2 ± 8#	23 ± 38δ	0 ± 0*	0 ± 0†	1 ± 6#
Physical-activity score	8 ± 5δ	5 ± 4*	4 ± 2†	Not done	13 ± 7δ	7 ± 6*	7 ± 4†	Not done	11 ± 7δ	6 ± 5*	5 ± 3†	Not done
Age (years)	55 ± 8δ	56 ± 10	53 ± 10	61 ± 10#	54 ± 8	58 ± 11*	57 ± 11	56 ± 12	54 ± 8δ	57 ± 10*	54 ± 10	58 ± 12#
Weight (kg)	80 ± 16δ	63 ± 8*	79 ± 6	80 ± 15	82 ± 11δ	77 ± 9*	90 ± 9†	92 ± 22#	81 ± 14δ	70 ± 11*	82 ± 9	87 ± 20#
Height (m)	1.56 ± 0.06	1.56 ± 0.07	1.57 ± 0.05	1.54 ± 0.06	1.70 ± 0.06	1.70 ± 0.06	1.68 ± 0.08	1.69 ± 0.07	1.64 ± 0.09	1.63 ± 0.10	1.61 ± 0.08†	1.63 ± 0.10
Body mass index (kg/m^2)	33 ± 6δ	26 ± 2*	32 ± 1	34 ± 6	28 ± 4δ	26 ± 2*	32 ± 1†	32 ± 7#	30 ± 5δ	26 ± 2*	32 ± 1†	33 ± 6#
Parity (numerical)	4 ± 2δ	6 ± 3*	6 ± 2†	5 ± 3#
Dyspnearest (VAS)	0 ± 0	0 ± 0	0 ± 0	0 ± 0	0 ± 0δ	0 ± 0	0 ± 0	1 ± 1#	0 ± 0δ	0 ± 0	0 ± 0	0 ± 1#
Dyspneaend (VAS)	3 ± 2δ	0 ± 0*	0 ± 0†	5 ± 2#	2 ± 2δ	0 ± 0*	0 ± 0†	4 ± 2#	2 ± 2δ	0 ± 0*	0 ± 0†	4 ± 2#
Heart raterest (%)	47 ± 7δ	45 ± 5*	46 ± 6	50 ± 7	46 ± 8	48 ± 6*	48 ± 6	47 ± 6	46 ± 7	47 ± 6	47 ± 6	48 ± 7
Heart rateend (%)	69 ± 10	71 ± 9	73 ± 10	68 ± 11	67 ± 12δ	87 ± 11*	85 ± 12†	73 ± 11#	68 ± 11δ	79 ± 13*	77 ± 12†	71 ± 11
Systolic pressurerest (mmHg)	131 ± 14δ	123 ± 16*	126 ± 13	139 ± 29	129 ± 12	136 ± 22*	132 ± 16	136 ± 20#	130 ± 13δ	130 ± 21	128 ± 14	137 ± 24#
Systolic pressureend (mmHg)	150 ± 17δ	152 ± 27	164 ± 25†	165 ± 31#	147 ± 16δ	176 ± 36*	178 ± 36†	158 ± 37	148 ± 16δ	164 ± 34*	168 ± 29†	161 ± 35#
Diastolic pressurerest (mmHg)	80 ± 9δ	72 ± 13*	76 ± 11	83 ± 19	79 ± 7	81 ± 16	76 ± 15	83 ± 11#	79 ± 8δ	76 ± 15	76 ± 13	83 ± 14#
Diastolic pressureend (mmHg)	86 ± 12δ	76 ± 13*	83 ± 11	91 ± 16	87 ± 9δ	79 ± 20*	87 ± 26	91 ± 14	86 ± 11δ	78 ± 17*	84 ± 17	91 ± 15#
Oxy-satrest (%)	98 ± 1δ	98 ± 1	97 ± 1†	96 ± 2#	98 ± 1δ	98 ± 1	97 ± 1	96 ± 2#	98 ± 1δ	98 ± 1	97 ± 1†	96 ± 2#
Oxy-satend (%)	97 ± 2δ	98 ± 1	97 ± 2	94 ± 5#	97 ± 2δ	97 ± 1	97 ± 1	94 ± 6#	97 ± 2δ	97 ± 1	97 ± 1	94 ± 5#
6MWD
(m)	513 ± 63δ	556 ± 75*	538 ± 73	398 ± 98#	609 ± 67δ	716 ± 82*	688 ± 72†	572 ± 97#	566 ± 81δ	636 ± 112*	585 ± 100	507 ± 129#
(%)	98 ± 11δ	100 ± 10	100 ± 8	82 ± 18#	84 ± 9δ	100 ± 8*	101 ± 7†	83 ± 11	90 ± 12δ	100 ± 9*	100 ± 8†	83 ± 14#
Percentage of patients with the following characteristics
Cigarette use	2%	0%	0%	0%	67%	0%*	0%†	68%	38%	0%*	0%†	42%
Narghile use	0%	0%	0%	0%	15%	0%*	0%†	16%	8%	0%*	0%†	10%
Chronic respiratory diseases	7%	0%*	0%†	82%#	13%	0%*	0%	63%#	10%	0%*	0%†	69%#
Arterial hypertension	44%	0%*	0%†	41%	31%	0%*	0%†	24%	37%	0%*	0%†	31%
Dyslipidemia history	18%	0%*	0%†		11%	0%*	0%		14%	0%*	0%†
Cardiovascular diseases	7%	0%*	0%†	14%	7%	0%*	0%	16%	7%	0%*	0%†	15%
Surgery history	38%	0%*	0%†	14%#	15%	0%*	0%†	3%#	25%	0%*	0%†	7%#
Beta-blocker use	13%	0%*	0%†	18%	7%	0%*	0%	5%	10%	0%*	0%†	10%
Low socioeconomic level	60%	70%	76%	91%#	16%	13%	59%†	19%	36%	41%	71%†	46%
Low schooling level	49%	70%*	66%	Not done	27%	53%*	12%	Not done	37%	61%*	49%	Not done
Sedentary status	71%	87%*	95%†	Not done	33%	72%*	71%†	Not done	50%	80%*	87%†	Not done
Obesity	69%	0%*	100%†	82%	31%	0%*	100%†	68%#	48%	0%*	100%†	73%#

Notes:

* P < 0.05 (probability, t-test or chi-squared test), PG vs CG1;

† P < 0.05 (probability, t-test or chi-squared test), PG vs CG2;

# P < 0.05 (probability, t-test or chi-squared test), PG vs CG3;

δ analysis of variance.

Abbreviations: 6MWD, 6-minute walk distance; oxy-sat, oxyhemoglobin saturation; PY, pack-years: NY, narghile-years; VAS, visual analogue scale.

Figure A1 The measured 6-minute walk distance (6MWD) of subgroups of non-insulin-dependent-diabetes mellitus males and females, according to age-group.

Notes: Data are shown as box-and-whisker plots illustrating the mean ± standard deviation; P, comparison male versus female (paired t-test).
Abbreviation: NS, not significant.

Table A1 Calculation of absolute cardiovascular disease risk³²

	Score
Age ≥ 50 years for males	+1
Age ≥ 60 years for females
Family history of premature coronary heart disease: Myocardial infarction or sudden death < 55 years with the father or a relative of first degree of male gender Myocardial infarction or sudden death < 65 years with the mother or a relative of first degree of female gender	+1
Current smoking or stopped less than 3 years	+1
Treated or untreated permanent arterial hypertension	+1
Presence of left ventricular hypertrophy	+1
Treated or untreated non-insulin-dependent diabetes mellitus	+1
High-density lipoprotein cholesterol ≤ 1.0 mmol/L	+1
High-density lipoprotein cholesterol ≥ 1.5 mmol/L	−1

Table A2 Univariate analysis between 6-minute walk distance and the non-insulin-dependent diabetes mellitus patients’ group data

	Females (n = 45)	Males (n = 55)	Total sample (n = 100)
Smoking status, medical, surgical, and obstetric history
Cigarette use
Yes	Not done	595 ± 59	597 ± 59
No		637 ± 75*	547 ± 86*
Narghile use
Yes	Not done	608 ± 69	616 ± 54
No		616 ± 54	562 ± 81
Chronic respiratory diseases
Yes	562 ± 31	588 ± 46	580 ± 42
No	510 ± 64	612 ± 69	564 ± 84
Arterial hypertension
Yes	521 ± 42	587 ± 53	551 ± 58
No	507 ± 76	619 ± 71	574 ± 91
Dyslipidemia
Yes	514 ± 69	607 ± 86	554 ± 88
No	513 ± 63	609 ± 65	568 ± 80
Cardiovascular diseases
Yes	471 ± 96	571 ± 91	528 ± 100
No	516 ± 61	612 ± 65	569 ± 79
Dysthyroid
Yes	537 ± 15	Not done	537 ± 15
No	511 ± 66		567 ± 82
Diabetic retinopathy
Yes	461 ± 101	577 ± 47	534 ± 88
No	577 ± 60	612 ± 68	569 ± 80
Surgical history
Yes	497 ± 69	595 ± 69	528 ± 82
No	523 ± 52	611 ± 67	578 ± 25*
Parity
Low	528 ± 52
High	467 ± 74*
Medication use
Beta-blocker use
Yes	491 ± 66	593 ± 43	532 ± 76
No	517 ± 63	610 ± 69	570 ± 81
Diuretic use
Yes	551 ± 43	Not done	571 ± 54
No	511 ± 64		566 ± 82
Socioeconomic, schooling, and physical activity levels
Socioeconomic level
Low	497 ± 66	590 ± 50	520 ± 74
High	539 ± 52*	613 ± 70	592 ± 73*
Schooling level
Low	494 ± 65	601 ± 50	537 ± 80
High	532 ± 56*	612 ± 73	583 ± 77*
Physical activity level
Sedentary	502 ± 62	616 ± 71	543 ± 69
Active	542 ± 59	605 ± 66	589 ± 69*
Metabolic characteristics
Obesity
Yes	511 ± 57	584 ± 47	537 ± 64
No	518 ± 78	620 ± 72	592 ± 86*
Uncontrolled diabetes
Yes	504 ± 74	606 ± 64	562 ± 85
No	515 ± 47	613 ± 73	571 ± 75
Measured dyslipidemia
Yes	511 ± 58	610 ± 76	565 ± 84
No	519 ± 75	608 ± 47	567 ± 75
Anthropometric data and parity
Age (years)	−0.54**	−0.25**	−0,34**
Weight (kg)	0.09	−0.10	0.03
Height (m)	0.24	0.20	0.57**
Body mass index (kg/m^2)	0.02	−0.22	−0.31**
Parity (numerical)	−0.44**
Metabolic data
Fasting glycemia (mmol/L)	0.05	−0.03	0.01
Glycated hemoglobin (%)	−0.16	0.06	0.01
Triglycerides (mmol/L)	−0.04	0.09	0.13
Total cholesterol (mmol/L)	0.01	0.23	0.01
HDL-cholesterol (mmol/L)	−0.08	0.16	0.03
LDL-cholesterol (mmol/L)	0.04	0.09	−0.09
Physical activity and absolute cardiovascular disease risk (ACVDR) scores
Activities
Daily	−0.11	0.02	−0.36**
Sporting	0.16	−0.18	0.19**
Leisure	0.07	0.28**	0.31**
Physical	0.15	−0.05	0.24**
ACVDR score	0.04	−0.28**	0.21**
6MWT resting data
Dyspnea (VAS)	0.23	−0.21	−0.05
Heart rate (bpm)	0.29**	−0.17	−0.04
Systolic pressure (mmHg)	−0.04	−0.30**	−0.20**
Diastolic pressure (mmHg)	0.25	−0.21	−0.01
Oxy-sat (%)	0.18	0.29**	0.21**

Notes: Data are expressed in means ± standard deviation;

* P (probability, t-test) < 0.05;

** P (coefficient of correlation) < 0.05.

Abbreviations: HDL, high-density lipoprotein; LDL, low-density lipoprotein; 6MWT, 6-minute walk test; VAS, visual analog scale; bpm, beats per minute; oxy-sat, oxyhemoglobin saturation.

Table A3 Frequency in the present study and in the literature of risk factors and certain comorbidities in non-insulin-dependent diabetes mellitus^33–36

	Frequency of the phenomenon in the present study	Prevalence of the phenomenon in the literature
Smoking (cigarettes, narghile)	46	64
Sedentary status	50	38
Low socioeconomic level	36	38
Obesity	48	52
Dyslipidemia	67	50
Arterial hypertension	37	49
Cardiovascular diseases	7	25
Chronic respiratory diseases	10	4.7
Diabetic retinopathy	8	29

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