Relationship Between Muscle Cramps and Diabetic Retinopathy in Patients with Type 2 Diabetes

Figures & data

Figure 1 Muscle cramps questionnaire to capture description of muscle cramps (onset, frequency, duration, and localization) and severity of pain by visual analogue scale for pain (Wong-Baker FACES pain rating scale).

Table 1 Clinical Characteristics of All Patients (n=150)

	Patients with Cramps	Patients without Cramps	P value
Age (year)	61 (55–66)	58 (50–66)	0.205
Male (%)	75% (54/72)	56% (44/78)	0.149
Smoking (%)	40% (29/72)	46% (34/78)	0.478
Alcohol drinking (%)	43% (31/72)	46% (36/78)	0.392
BMI (kg/m^2)	24.6 (23.4–27.1)	25.4 (23.2–27.7)	0.961
MBP (mmHg)	97.6 (92.3–108.3)	96.7 (89.3–106.6)	0.595
HbA1C (%)	8.1 (6.8–10.0)	8.0 (7.0–9.1)	0.288
Cr (umol/L)	72 (60–84.5)	70 (58.5–78.0)	0.426
ALB (g/L)	41.6 (38.2–45.0)	43.3 (41.2–46.2)	0.006
K (mmol/L)	4.16 (3.93–4.41)	4.15 (3.92–4.38)	0.098
Ca (mmol/L)	2.28 (2.19–2.34)	2.30 (2.23–2.35)	0.165
Mg (mmol/L)	0.86 (0.81–0.92)	0.86 (0.81–0.90)	0.897
VIT-D (ng/mL)	19.3 (11.9–24.6)	19.0 (13.6–23.5)	0.618
DR(%)	61% (44/72)	38% (30/78)	0.009
NPDR((%)	38% (28/72)	35%(27/78)	0.587
PDR(%)	22% (16/72)	4% (3/78)	0.001

Abbreviations: BMI, body mass index; MBP, mean blood pressure; Cr, creatinine; AlB, albumin, VIT-D, 25-OH-vitamin D3; DR, diabetic retinopathy; PDR, proliferative diabetic retinopathy.

Figure 2 Frequency of muscle cramps, severity of pain, time of day of muscle cramps, duration of muscle cramps.

Abbreviation: VAS, visual analogue scale.

Table 2 Relationship Between Muscle Cramps and Diabetic Retinopathy a After Controlling for Confounding Factors

	OR (95% CI)	P
Model 1
Age (year)	1.01 (0.98–1.05)	0.427
DR (no DR as reference)	2.46 (1.27–4.76)	0.011
Model 2
Age (year)	1.01 (0.98–1.05)	0.47
HbA1C	1.13 (0.97–1.31)	0.118
Duration of diabetes (year)	1.01 (0.97–1.06)	0.591
DR (no DR as reference)	2.48 (1.24–4.95)	0.01
Model 3
Age (year)	1.01 (0.97–1.05)	0.524
HbA1C (%)	1.03 (0.83–1.23)	0.923
Duration of diabetes (year)	1.01 (0.98–1.08)	0.214
ALB(mmol/L)	0.90 (0.82–1.00)	0.041
Ca(mmol/L)	3.00 (0.04–211.6)	0.612
Mg(mmol/L)	0.88 (0.03–317.4)	0.65
VIT-D (ng/mL)	1.00 (0.95–1.06)	0.808
DR (no DR as reference)	2.18 (1.01–4.69)	0.046

Notes: Model 1 was adjusted for age. Model 2 includes all variables in model 1 plus HbA1c and duration of diabetes (variables associated with diabetic retinopathy), Model 3 includes all variables in model 2 plus albumin, vitamin D, calcium, and magnesium.

Table 3 Associations Between Severity of DR and Muscle Cramps in Type 2 Diabetes

Variable	Model 1			Model 2			Model 3
	OR (95% CI)	p value	p value for Trend	OR (95% CI)	p value	p value for Trend	OR (95% CI)	p value	p value for Trend
Patients without DR	1 [Reference]		p<0.05	1 [Reference]		p<0.05	1 [Reference]		p<0.05
Patients with NPDR	1.73 (0.85–3.51)	0.13		1.83 (0.89–3.78)	0.104		1.76 (0.79–3.01)	0.164
Patients with PDR	9.04 (2.42–33.8)	0.01		11.8 (2.41–58.1)	0.02		8.02 (1.41–45.4)	0.019

Notes: Model 1 was adjusted for age. Model 2 includes all variables in model 1 plus HbA1c and duration of diabetes (variables associated with diabetic retinopathy), Model 3 includes all variables in model 2 plus albumin, vitamin D, calcium, and magnesium.

Table 4 Relationships Between Muscle Cramp Frequency, Duration Length, Pain Severity, Location of Muscle Cramps, Time of Day, and Diabetic Retinopathy

	No DR (%)	NPDR (%)	PDR (%)
Frequency
Muscle cramp at least once a week	29% (7/24)	42% (10/24)	29% (7/24)
Muscle cramp at least once a month	39% (12/31)	45% (11/31)	26% (8/31)
Muscle cramp once within the last 3 months	53% (9/17)	41% (7/17)	6% (1/17)
No muscle cramp	62% (48/78)	34% (27/78)	4% (3/78)
p value	0.019	0.903	0.001
p for trend	0.002	0.505	0.001
Severity
VAS>3	26% (7/27)	48% (13/27)	26% (7/27)
VAS≤3	47% (21/45)	35% (16/45)	18% (8/45)
No muscle cramp	61% (48/78)	35% (27/78)	4% (3/78)
p value	0.005	0.437	0.004
p for trend	0.001	0.267	0.001
Duration
Lasting more than 10 minutes	0% (0/2)	100% (2/2)	0% (0/2)
Lasting 1–10 minutes	35% (19/54)	41% (22/54)	24% (13/54)
Lasting for less than 1 minute	56% (9/16)	31% (5/16)	13% (2/16)
No muscle cramp	61% (48/78)	35% (27/78)	4% (3/78)
p value	0.011	0.248	0.005
p for trend	0.001	0.256	0.001
Time of day
Both day and night	75% (6/8)	12.5% (1/8)	12.5% (1/8)
Night	39% (19/49)	47% (23/49)	14% (7/49)
Day	20% (3/15)	33% (5/15)	47% (7/15)
No muscle cramp	61% (48/78)	35% (27/78)	4% (3/78)
p value	0.03	0.222	0.001
p for trend	0.099	0.712	0.058