Table 2.

The overall effect of vitamin D supplement on the HbA1C and FBS in patients with diabetes based on continent, age, BMI, diabetes duration, dose of intervention, and follow-up duration.

Variables		Category	No. study	Pooled MSD (95% CI)	Heterogeneity assessment between studies			Heterogeneity assessment between subgroup		Publication bias assessments
					I 2	p value	Q	Q	p value	β	SE	p value
HbA1C	Overall SMD		45 (61)	−0.15 (−0.29, −0.2)	79.76%	≤0.001	296.37	—	—	−1.48	0.806	0.065
	Continent	Europe	12 (22)	−0.08 (−0.17, 0.02)	5.45%	0.39	22.21	7.08	0.03
		Asia	30 (33)	−0.32 (−0.53, −0.11)	84.18%	≤0.001	102.27
		America	3 (6)	0.30 (−0.19, 0.79)	88.08%	≤0.001	41.94
	Age	<60	28 (30)	−0.35 (−0.56, −0.13)	84.56%	≤0.001	187.79	8.44	≤0.001
		>60	13 (25)	0.05 (−0.11, 0.22)	66.83%	≤0.001	72.36
	BMI	<30	22 (28)	−0.32 (−0.52, −0.11)	80.92%	≤0.001	141.48	6.63	0.01
		>30	12 (20)	0.06 (−0.15, 0.26)	75.76%	≤0.001	78.38
	Disease duration	<10	14 (16)	−0.18 (−0.49, −0.13)	86.44%	≤0.001	110.64	0.62	0.43
		>10	3 (4)	−0.49 (−1.19, 0.21)	88.49%	≤0.001	26.07
	Intervention	<50,000	20 (29)	−0.22 (−0.46, 0.02)	86.38%	≤0.001	205.55	0.78	0.68
		50,000–100,000	22 (25)	−0.15 (−0.31, −0.02)	72.25%	≤0.001	86.50
		>100,000	5 (7)	−0.08 (−0.28, 0.12)	0.00	0.84	2.76
	Follow-up duration	8 weeks	10 (11)	−0.38 (−0.88, 0.12)	90.30%	≤0.001	103.08	30.53	≤0.001
		12 weeks	19 (19)	−0.29 (−0.51, −0.06)	75.25%	≤0.001	72.73
		14 weeks	1 (1)	−1.63 (−2.28, −1.01)	—	—	—
		16 weeks	5 (7)	−0.02 (−0.17, 0.12)	0.00%	0.76	3.38
		24 weeks	18 (18)	−0.03 (−0.13, 0.07)	0.00%	0.68	13.87
		36 weeks	2 (2)	0.62 (−1.01, 2.26)	93.69%	≤0.001	15.85
		48 weeks	3 (3)	−0.07 (−0.36, −0.21)	3.63%	0.35	2.08
FBS	Overall SMD		40 (50)	−0.28 (−0.40, −0.15)	70.13%	≤0.001	164.07	—	—	−2.50	0.812	0.002
	Continent	Europe	8 (13)	−0.19 (−0.31, −0.07)	0.00%	0.83	7.42	1.12	0.57
		Asia	31 (36)	−0.30 (−0.47, −0.12)	77.56%	≤0.001	155.97
		America	1 (1)	−0.14 (−0.61, 0.33)	—	—	—
	Age	<60	26 (29)	−0.19 (−0.34, −0.04)	63.01%	≤0.001	75.70	0.00	1.00
		>60	12 (17)	−0.19 (−0.30, −0.08)	0.00%	0.60	13.96
	BMI	<30	22 (28)	−0.24 (−0.38, −0.09)	54.51%	≤0.001	59.35	0.96	0.33
		>30	12 (14)	−0.14 (−0.26, −0.02)	2.92%	0.42	13.39
	Disease duration	<10	16 (18)	−0.14 (−0.34, 0.06)	71.02%	≤0.001	58.65	0.26	0.61
		>10	1 (1)	0.00 (−0.50, 0.50)	—	—	—
	Intervention	<50,000	17 (24)	−0.44 (−0.69, −0.2)	78.84%	≤0.001	108.70	5.23	0.07
		50,000–100,000	19 (22)	−0.21 (−0.34, −0.08)	45.65%	0.01	38.64
		>100,000	4 (4)	0.12 (−0.34, 0.57)	67.71%	0.03	9.29
	Follow-up duration	8 weeks	9 (9)	−0.25 (−0.58, 0.08)	76.01%	≤0.001	33.35	1.34	0.97
		12 weeks	18 (19)	−0.25 (−0.43, −0.06)	60.43%	≤0.001	45.49
		10 weeks	1 (1)	−0.19 (−0.66, 0.28)	—	—	—
		16 weeks	2 (2)	−0.15 (−0.57, 0.28)	14.88%	0.28	1.17
		24 weeks	16 (16)	−0.38 (−0.64, −0.12)	81.61%	≤0.001	81.58
		36 weeks	1 (1)	−0.40 (−1.12, 0.33)	—	—	—
		48 weeks	2 (2)	−0.19 (−0.83, 0.45)	47.51%	0.17	1.91