Table 4.

Subgroup analyses for studies reporting crude effect estimates

Subgroups	No. of studies	OR (95% CI)	P value	I2 (p value)	P value for within-stratum heterogeneity	P value for between-stratum heterogeneity
Compared groups
Insulin versus oral drugs	17	1.61 (1.35 to 1.93)	<0.05	62.6%	<0.05	0.49
Insulin versus non-drugs	6	1.89 (1.25 to 2.88)	<0.05	68.2%	<0.05
Region
USA	4	1.53 (1.21 to 1.93)	<0.05	75.4%	<0.05	0.31
Asia	9	1.60 (1.22 to 2.10)	<0.05	75.4%	0.05
Europe	7	1.59 (1.13 to 2.22)	<0.05	45.3%	<0.05
Africa	2	1.77 (1.23 to 2.54)	<0.05	0.0	0.85
South America	1	1.28 (0.50 to 3.27)	>0.05	–	–
Sample size
≥1000	7	1.64 (1.39 to 1.93)	<0.05	77.5%	<0.05	0.71
<1000	17	1.56 (1.27 to 1.91)	<0.05	46.7%	<0.05
Mean age
≥60.0	10	1.60 (1.30 to 1.97)	<0.05	61.8%	<0.05	0.92
<60.0	10	1.57 (1.18 to 2.09)	<0.05	68.0%	<0.05
Percentage male (%)
≥50.0	13	1.59 (1.29 to 1.96)	<0.05	75.1%	<0.05	0.82
<50.0	11	1.55 (1.43 to 1.68)	<0.05	0.0	0.71
Prevalence of depression
≥20%	14	1.84 (1.59 to 2.12)	<0.05	11.7%	0.33	<0.05
<20%	10	1.43 (1.19 to 1.70)	<0.05	74.0%	<0.05
Newcastle-Ottawa Scale
7 or 8	11	1.45 (1.16 to 1.82)	<0.05	72.3%	<0.05	0.22
<7	13	1.72 (1.47 to 2.00)	<0.05	42.8%	0.05