. 2014 Nov 3;6(2):112–123. doi: 10.1111/jdi.12288

Table 2.

Epidemiological surveys comparing serum total testosterone levels in men with and without type 2 diabetes

Source	Site	Year of publication	Study design	No. participants	Age (years)	Findings
Barrett-Connor et al.¹	USA	1992	Cross-sectional	132	53–88	Low serum total testosterone (defined by < 15.9 nmol/L) was significantly more frequent and lower in men with T2DM (21%, 14.7 ± 5.79 nmol/L) as compared with men without (13%, 17.4 ± 4.74 nmol/L)
				T2DM 44
				No T2DM 88
Oh JY et al.¹²⁴	USA	2002	Prospective	294	55–89	Odds for new T2DM was 2.7 (95% CI 1.1–6.6) for men in the lowest quartile of total testosterone
			8 years	Incident T2DM 26
			8 years	No T2DM 268
Ding EL et al.²	Worldwide	2006	Meta-analysis of cross-sectional and prospective studies	7,100	44–80	Serum total testosterone was significantly lower in men with T2DM in cross-sectional studies (−2.66 nmol/L, 95% CI −3.45 to −1.86) and in prospective studies (−2.48 nmol/L, 95% CI −4.4 to −0.93)
				Cross-sectional T2DM 964
				No T2DM 2,918
				Prospective T2DM 391
				No T2DM 2,827
Cao J et al.¹²⁵	China	2011	Cross-sectional	492	71–73	Serum total testosterone was significantly lower in subjects with DM (13.8 ± 4.7 nmol/L) than those without (17.1 ± 6.1 nmol/L; P < 0.01)
				T2DM 129
				No T2DM 363

CI, confidence interval; DM, diabetes mellitus; T2DM, type 2 diabetes mellitus.