Table 3. Pooled odds ratios (ORs)^a for diabetes mellitus and two associated risk factors.

Variable	Diabetes mellitus				Impaired fasting glycaemia				Impaired glucose tolerance
	nb	OR (95% CI)	Pc		nb	OR (95% CI)	Pc		nb	OR (95% CI)	Pc
All data sets	35	1.01 (0.91–1.11)			11	1.56 (1.20–2.03)			21	0.84 (0.72–0.98)
Area of residence			0.009				0.56				< 0.001
Combined	9	1.17 (1.04–1.31)			6	1.61 (1.14–2.26)			7	0.69 (0.59–0.81)
Periurban	2	0.70 (0.42–1.18)							2	0.79 (0.46–1.37)
Rural	11	0.98 (0.80–1.20)			2	2.21 (0.87–5.64)			6	0.82 (0.61–1.09)
Urban	13	0.86 (0.73–1.01)			3	1.24 (0.71–2.19)			6	1.33 (1.03–1.72)
Subregion of residence			< 0.001				0.019				0.001
Middle Africa	2	1.44 (1.31–1.59)			1	1.04 (0.65–1.65)			2	0.73 (0.49–1.09)
Eastern Africa	21	1.08 (1.01–1.15)			9	1.65 (1.35–2.02)			11	0.71 (0.59–0.84)
Southern Africa	12	0.80 (0.69–0.92)			1	5.19 (1.75–15.38)			8	1.30 (0.99–1.70)
Ethnicity of subjects			0.012				0.066				0.002
African	24	1.12 (1.00–1.25)			7	1.30 (0.96–1.74)			11	0.81 (0.66–0.99)
Indian	2	0.69 (0.52–0.94)							2	1.66 (1.10–2.50)
Multi-ethnic	9	1.00 (0.87–1.14)			4	1.93 (1.42–2.62)			8	0.73 (0.60–0.89)
Study year			0.125				0.81				0.61
Before 1991	9	0.90 (0.73–1.11)			1	1.94 (0.84–4.48)			4	0.90 (0.62–1.31)
1991–1999	13	0.96 (0.83–1.12)			4	1.41 (0.88–2.27)			10	0.90 (0.68–1.19)
After 1999	13	1.13 (0.99–1.30)			6	1.58 (1.09–2.30)			7	0.74 (0.55–1.01)
Country income level			0.008				0.006				0.028
Low	14	1.21 (1.06–1.37)			6	1.18 (0.89–1.57)			5	0.70 (0.52–0.95)
Lower middle	4	1.16 (0.75–1.80)							4	0.50 (0.29–0.87)
Upper middle	17	0.93 (0.83–1.03)			5	2.05 (1.56–2.69)			12	0.99 (0.80–1.23)

CI, confidence interval.

^a ORs represent the odds in men versus the odds in women.

^b Number of data sets included in the analysis.

^c P-value for the category, estimated in a Q-test.