Table 4.

Sensitivity and subgroup analysis based on the normalization of blood glucose

	Group	No. of studies	No. of participants	RR	95% CI	Z	P (effect)	I 2	χ2	P (het)
Treatment duration	≥ 12 months	5	967	0.71	[0.63, 0.80]	5.43	< 0.00001	0%	1.04	0.90
	< 12 months	1	60	0.50	[0.30, 0.84]	2.63	0.009	–	–	–
Sample size	≥ 100	4	907	0.71	[0.62, 0.80]	5.29	< 0.00001	0%	1.02	0.80
	< 100	2	120	0.61	[0.42, 0.86]	2.77	0.006	9%	1.09	0.30
Use of placebo	Used	5	967	0.69	[0.61, 0.78]	5.80	< 0.00001	0%	2.62	0.62
	Not used	1	60	0.73	[0.45, 1.20]	1.25	0.21	–	–	–
Publication language	English	1	420	0.70	[0.57, 0.86]	3.45	0.0006	–	–	–
	Chinese	5	607	0.69	[0.59, 0.80]	4.85	< 0.00001	0%	2.65	0.62

Normalization of blood glucose was analyzed according to different criteria based on treatment duration, sample size, use of placebo, and publication language. RR is risk ratio, CI is confidence interval. Z and P (effect) evaluated the statistics of overall effect; I ² and P (het) were computed to assess heterogeneity