Low total testosterone is associated with increased risk of incident type 2 diabetes mellitus in men: results from the Study of Health in Pomerania (SHIP)

Figures & data

Table I. Baseline characteristics of men with total testosterone concentrations below and above the 10th percentile.

	Testosterone <10th percentile (n = 130)	Testosterone ≥10th percentile (n = 1209)
Age (years)	50 (15)	49 (15)
Waist circumference (cm)	99.7 (12.0)	94.5 (11.0)*
Body mass index (kg/m^2)	28.9 (4.2)	27.3 (3.8)*
Smoking^† (%)
Never smoker	30.0	26.6
Former smoker	46.9	42.9
1–14	7.7	9.6
≥15	15.4	21.0
Physical activity (%)	38.5	45.0
Serum total testosterone (nmol/l)	9.1 (8.1; 9.6)	16.6 (13.8; 20.4)^‡
Random plasma Glucose (mmol/l)	5.4 (5.0; 6.0)	5.3 (4.9; 5.8)
Haemoglobin A1c (%)	5.4 (4.8; 5.8)	5.3 (5.0; 5.7)
Cholesterol (mmol/l)	5.7 (5.0; 6.5)	5.7 (5.0; 6.5)
Triglycerides (mmol/l)	2.2 (1.4; 3.1)	1.7 (1.1; 2.5)*
HDL cholesterol (mmol/l)	1.2 (1.0; 1.5)	1.3 (1.1; 1.5)
LDL cholesterol (mmol/l)	3.5 (2.7; 4.3)	3.6 (2.9; 4.3)
Incident type 2 diabetes mellitus (%)	13.1	4.2*

Data are percentages, mean (SD) or median (25th; 75th).

*p < 0.05 for tested differences between men with total testosterone concentrations below and above the 10th percentile based on the χ²-test (nominal data) or the Mann–Whitney U-test (continuous data).

^†Never smoking include occasional smoking (<1 cigarette per day).To convert testosterone from SI units (nmol/l) into conventional units (ng/dl), multiply by 28.82; Glucose from mmol/l into mg/dl by 0.0555.

^‡No test for comparison.

Table II. Baseline characteristics of respondents and non-respondents.

	Respondents (n = 1339)	Non-respondents (n = 528)
Age (years)	50 (37; 61)	58 (35; 70)*
Diagnosed diabetes mellitus (%)
Type 1	0.2	0.2
Type 2	7.8	11.0
Undiagnosed^†	0.2	0.6*
Serum total testosterone (nmol/l)	16.0 (12.9; 19.9)	16.4 (12.7; 21.1)
Serum total testosterone (nmol/l)
<10th percentile	13.0	11.8
20–29	12.5	10.5
30–39	10.7	8.4
40–49	9.6	8.6
50–59	10.3	9.4
60–69	10.2	8.0
>70
Random plasma glucose (mmol/l)	5.3 (5.0; 5.8)	5.5 (5.0: 6.3)*
Hemoglobin A1c (%)	5.3 (4.9; 5.7)	5.4 (5.0; 5.9)*
Waist circumference (cm)	94.5 (87.0; 102.2)	95.5 (87.1; 103.8)
Body mass index (kg/m^2)	27.2 (24.8; 29.7)	27.6 (24.7; 30.0)
Smoking (cigarettes per day) (%)
Never smoker^‡	26.9	18.4
Former smoker	43.2	42.2
1–14	9.4	13.6
≥15	20.5	24.4*
Physical activity (%)	44.4	37.7*

Data are percentages, mean (SD) or median (25th; 75th).

*p < 0.05 for tested differences between respondents and non-respondents based on the χ²-test (nominal data) or the Mann–Whitney U-test (continuous data).

^†Undiagnosed T2DM is defined by random plasma glucose ≥11.1 mmol/l (WHO) [23].

^‡Never smoker include occasional (<1 cigarette per day). To convert testosterone from SI units (nmol/l) into conventional units (ng/dl), multiply by 28.82; Glucose from mmol/l into mg/dl by 0.0555.

Table III. Estimated crude and adjusted odds ratios for the association of total testosterone associated with incident type 2 diabetes mellitus.

	Testosterone <10th percentile*	Testosterone <8 nmol/l^†	Testosterone <10.4 nmol/l^†	Testosterone <12 nmol/l^†	Testosterone <16 nmol/l^†
Crude Model	3.4 (1.9; 6.1)	5.7 (2.4; 13.7)	3.5 (2.0–6.2)	2.7 (1.6; 4.6)	2.4 (1.4–4.0)
Adjusted Model^‡	3.0 (1.6; 5.7)	4.5 (1.6; 12.4)	2.5 (1.3–4.7)	1.9 (1.1; 3.4)	1.6 (0.9–3.0)

*Total testosterone concentrations <10th percentile vs. ≥10th percentile by 10 year age strata.

^†Total testosterone concentration vs. >8 nmol/l; vs. ≥8 nmol/l; >14.4 nmol/l; vs. ≥14.4 nmol/l; >12 nmol/l; vs. ≥12 nmol/l; >16 nmol/l; vs. ≥16 nmol/l.

^‡Model: adjusted for age (continuous), WC (continuous), smoking (non smoking as reference; exsmoker, 1–14 cigarettes/die, ≥15 cigarettes/die). To convert testosterone from SI units (nmol/l) into conventional units (ng/dl), multiply by 28.82.

Figure 1.  Odds ratio of the association between low total testosterone concentrations and incident type 2 diabetes mellitus for the responding full cohort (N = 1339 men/n = 68 cases) using different cut-offs [<10th percentile (N = 130/n = 17); <8 nmol/l (N = 32/n = 7); <10.4 nmol/l (N = 136/n = 18)]; <12nmol/l (N = 247/n = 25)] in comparison to weighted analyses accounted for drop out from baseline to follow-up.

World Health Organisation. Definition, diagnosis, and classification of diabetes mellitus and its complications: report of a WHO consultation. Part 1: diagnosis and classification of diabetes mellitus. GenevaWHO Department of Noncummunicable Disease Surveillance/NCD/NCS1999; 1–59.

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