Impact of Glycemic Control on Shoulder Proprioception in Type 2 Diabetes Mellitus: Mediating the Connection - Insights from a Cross-Sectional Analysis

Figures & data

Figure 1 Assessment of shoulder proprioception in (A) Flexion, (B) abduction, and (C) internal and external rotations.

Table 1 Demographic Characteristics of Diabetes and Asymptomatic Population

Variables	Diabetes Subjects (n=60)	Asymptomatic Subjects (n=60)	p value
Age in years	62.38 ± 7.43	63.01 ±8,81	0.135
BMI (kg/m^2)	25.24 ± 3.63	25.58 ±2.53	0.345
Duration of diabetes (years)	7.56 ± 3.21	–	–
HbA1c	7.36 ± 0.46	–	–

Note: Values are presented as mean ± standard deviation.

Abbreviations: BMI, Body Mass Index; HbA1c, Glycosylated Hemoglobin.

Table 2 Comparison of Shoulder Joint Position Sense Between T2DM and Asymptomatic Groups

Variables	Diabetes Subjects (n=117) (Mean ± SD)	Asymptomatic Subjects (n=142) (Mean ± SD)	95% CI of the Difference		Cohen’s d	SEM	MDC	p value
			Lower	Upper
Shoulder JPE in flexion (⁰)	4.32 ± 0.98	2.15 ± 0.27	1.23	3.11	1.35	0.85	1.98	<0.001
Shoulder JPE in Abduction (⁰)	4.90 ± 0.69	1.93 ± 0.44	0.98	2.96	1.54	1.03	2.96	<0.001
Shoulder JPE in medial rotation(⁰)	4.48 ± 0.99	2.11 ± 0.86	1.93	3.16	1.89	1.07	2.36	<0.001
Shoulder JPE in lateral rotation (⁰)	4.63 ± 0.89	1.97 ± 0.98	2.17	2.89	1.96	1.32	2.98	<0.001

Abbreviations: JPE, joint position error; CI, confidence interval; SEM, standard error of mean; MDC, minimal detectable change.

Table 3 The Relationship Between HbA1c Values and Shoulder Joint Position Errors in Patients with T2DM

		Shoulder JPE in Flexion (⁰)	Shoulder JPE in Abduction (⁰)	Shoulder JPE in Medial Rotation (⁰)	Shoulder JPE in Lateral Rotation (⁰)
HbA1c %	r	0.51	0.48	0.39	0.38
	p	<0.001	<0.001	<0.001	<0.001

Abbreviations: HbA1c, glycated hemoglobin; JPE, joint position error.

Figure 2 Scatter plot showcasing the correlation between glycated hemoglobin (HbA1c) levels and shoulder joint position errors (JPE) in degrees for different movements in patients with Type 2 Diabetes Mellitus (T2DM). Each point indicates the correlation coefficient (r) for the specified shoulder movement. Statistically significant correlations are observed with p-values less than 0.001 across all movements.

Table 4 Mediation Analysis of the Relationship Between HbA1c Levels, T2DM Status, and Shoulder Joint Position Sense

Path	Effect Description	Coefficient	Standard Error	t-value	p-value	Confidence Interval
A	Effect of HbA1c on Mediator (T2DM status)	0.60	0.10	6.00	0.002	[0.42, 0.78]
B	Effect of Mediator (T2DM status) on Shoulder JPS, controlling for HbA1c	0.25	0.08	3.12	0.001	[0.11, 0.39]
C (Total)	Total effect of HbA1c on Shoulder JPS	0.45	0.07	6.42	<0.001	[0.32, 0.58]
C’ (Direct)	Direct effect of HbA1c on Shoulder JPS, controlling for Mediator (T2DM status)	0.30	0.09	3.33	<0.001	[0.14, 0.46]
A*B (Indirect)	Indirect effect of HbA1c on Shoulder JPS through Mediator (T2DM status)	0.15	0.05	3.00	<0.001	[0.18, 0.56]

Notes: Path: Represents the different paths in the mediation analysis model. Coefficient: The numerical value representing the strength of the effect. Standard Error: Indicates the precision of the coefficient estimate t-value: The ratio of the coefficient to its standard error. Confidence Interval: Indicates the range within which the true population parameter is likely to fall.

Abbreviations: HbA1c, Hemoglobin A1c; T2DM, Type 2 Diabetes Mellitus; JPS, Joint Position Sense; CI, Confidence Interval.

Figure 3 Comprehensive Mediation Analysis: Coefficients and t-Values for HbA1c, T2DM Status, and Shoulder JPS Relationship.