Associations of black coffee and black coffee supplemented with milk with diabetes in China: A community-based cross-sectional study

Table 1 Characteristics of study participants not drink coffee and drink at least one cup of coffee per day, n (%)/median (interquartile range)

	All	Non-coffee drinkers	1 or more cups/day	P value1
	6876	5149 (75.00)	1727 (25.00)
Age, years				< 0.001
< 60	6275 (91.26)	4587 (89.09)	1688 (97.74)
≥ 60	601 (8.74)	562 (10.91)	39 (2.26)
Sex				0.167
Female	4308 (62.65)	3250 (63.12)	1058 (61.26)
Male	2568 (37.35)	1899 (36.88)	669 (38.74)
BMI, kg/m2				0.378
< 24	3439 (50.01)	2931 (56.92)	1004 (58.14)
≥ 24	3437 (49.99)	2218 (43.08)	723 (41.86)
Education				< 0.001
Primary	2442 (35.51)	2194 (42.61)	248 (14.36)
Secondary	1708 (24.84)	1321 (25.66)	387 (22.41)
Tertiary	2726 (39.65)	1634 (31.73)	1092 (63.23)
Smoking status				0.005
Never smokers	5958 (86.65)	4436 (86.15)	1522 (88.13)
Former smoker	194 (2.39)	164 (3.19)	30 (1.74)
Current smoker	724 (10.53)	549 (10.66)	175 (10.13)
Alcohol drinking status				0.036
Yes	202 (2.94)	164 (3.19)	38 (2.20)
No	6674 (97.06)	4985 (96.81)	1689 (97.80)
Physical activity				< 0.001
No exercise	3192 (46.42)	2476 (48.09)	716 (41.46)
Low intensity exercise	2121 (30.85)	1441 (27.99)	680 (39.37)
Moderate intensity exercise	875 (12.73)	667 (12.95)	208 (12.04)
High intensity exercise	688 (10.01)	565 (10.97)	123 (7.12)
Hypertension				< 0.001
Yes	1708 (24.84)	1383 (26.86)	325 (18.82)
No	5168 (75.16)	3766 (73.14)	1402 (81.18)
Diabetes				< 0.001
Yes	821 (11.94)	684 (13.28)	137 (7.93)
No	6055 (88.06)	4465 (86.72)	1590 (92.07)
Family history of diabetes				0.006
Yes	1238 (18.00)	889 (17.27)	349 (20.21)
No	5638 (82.00)	4260 (82.73)	1378 (79.79)
TC, nmol/L	5.26 (4.63, 5.97)	5.30 (4.67, 6.02)	5.14 (4.53, 5.84)	< 0.001
TG, nmol/L	1.20 (0.86, 1.80)	1.22 (0.87, 1,82)	1.15 (0.83, 1.73)	< 0.001
HDL-C, nmol/L	1.42 (1.22, 1.65)	1.43 (1.22, 1.66)	1.41 (1.21, 1.63)	0.019
LDL-C, nmol/L	2.93 (2.68, 3.42)	2.95 (2.48, 3.45)	2.87 (2.47, 3.37)	0.015

¹Differences between groups were compared by χ² test or Mann-Whitney U test or t test. P value of < 0.05 was considered to be statistically significant.

BMI: Body mass index; HDL-C: High-density cholesterol lipoprotein; LDL-C: Low-density cholesterol lipoprotein; TC: Total cholesterol; TG: Triglyceride.

Table 2 Relationship between coffee consumption and diabetes as well as glucose metabolism parameters

	Unadjusted		Model 11		Model 22
	OR (95%CI)	P value	OR (95%CI)	P value	OR (95%CI)	P value
Diabetes	0.56 (0.46-0.68)	< 0.001	0.64 (0.52-0.77)	< 0.001	0.79 (0.64-0.98)	0.029
High FBG	0.59 (0.48-0.74)	< 0.001	0.68 (0.55-0.85)	0.001	0.81 (0.64-1.03)	0.088
High 2h-PG	0.66 (0.59-0.74)	< 0.001	0.71 (0.64-0.80)	< 0.001	0.83 (0.73-0.95)	0.005
High HbA1c	0.56 (0.50-0.63)	< 0.001	0.61 (0.54-0.69)	< 0.001	0.76 (0.67-0.86)	< 0.001

¹Adjusted for sex, age, and body mass index.

²Further extended model 1 by incorporating adjustments for education level, smoking status, physical activity, alcohol consumption, hypertension, total cholesterol, triglycerides, high- and low-density cholesterol lipoprotein, family history of diabetes.

2h-PG: 2-hour blood glucose; CI: Confidence interval; FBG: Fasting plasma glucose; HbA1c: Glycated hemoglobin; OR: Odds ratio.

Table 3 Correlation analysis of coffee types

		Unadjusted		Model 11		Model 22
		OR (95%CI)	P value	OR (95%CI)	P value	OR (95%CI)	P value
Diabetes	Non-coffee drinkers (n = 5149)	Reference		Reference		Reference
	Black coffee (n = 457)	0.70 (0.50-0.96)	0.026	0.76 (0.55-1.05)	0.098	0.92 (0.65-1.29)	0.617
	Milk coffee (n = 1217)	0.52 (0.41-0.65)	< 0.001	0.60 (0.48-0.75)	< 0.001	0.75 (0.59-0.95)	0.017
High FBG	Non-coffee drinkers (n = 5149)	Reference		Reference		Reference
	Black coffee (n = 457)	0.60 (0.40-0.89)	0.011	0.66 (0.44-0.98)	0.037	0.75 (0.50-1.14)	0.177
	Milk coffee (n = 1217)	0.60 (0.46-0.76)	< 0.001	0.70 (0.55-0.91)	0.006	0.84 (0.64-1.10)	0.194
High 2h-PG	Non-coffee drinkers (n = 5149)	Reference		Reference		Reference
	Black coffee (n = 457)	0.83 (0.68-1.01)	0.068	0.90 (0.74-1.10)	0.299	1.05 (0.85-1.29)	0.678
	Milk coffee (n = 1217)	0.61 (0.53-0.69)	< 0.001	0.66 (0.58-0.76)	< 0.001	0.76 (0.66-0.88)	< 0.001
High HbA1c	Non-coffee drinkers (n = 5149)	Reference		Reference		Reference
	Black coffee (n = 457)	0.69 (0.57-0.84)	< 0.001	0.72 (0.59-0.88)	0.001	0.87 (0.70-1.07)	0.190
	Milk coffee (n = 1217)	0.52 (0.46-0.59)	< 0.001	0.58 (0.51-0.66)	< 0.001	0.72 (0.63-0.83)	< 0.001

¹Adjusted for sex, age, and body mass index.

²Further extended model 1 by incorporating adjustments for education level, smoking status, physical activity, alcohol consumption, hypertension, total cholesterol, triglycerides, high- and low-density cholesterol lipoprotein, family history of diabetes.

2h-PG: 2-hour blood glucose; CI: Confidence interval; FBG: Fasting plasma glucose; HbA1c: Glycated hemoglobin; OR: Odds ratio.

Table 4 Stratified analysis

	Count	OR (95%CI)	P value	P interaction value
Age, years		1.48 (0.69-3.20)		0.315
< 60	6275	0.78 (0.63-0.97)	0.025
≥ 60	601	1.01 (0.47-2.20)	0.978
BMI, kg/m2		0.97 (0.64-1.46)		0.869
< 24	3439	0.88 (0.62-1.27)	0.498
≥ 24	3437	0.75 (0.58-0.97)	0.028
Sex		0.90 (0.61-1.33)		0.609
Female	4308	0.83 (0.62-1.10)	0.183
Male	2568	0.74 (0.54-1.02)	0.063
Education level		0.89 (0.70-1.13)		0.335
Primary	2442	0.98 (0.68-1.42)	0.931
Secondary	1708	0.73 (0.48-1.10)	0.129
Tertiary	2726	0.70 (0.51-0.97)	0.033
Hypertension		1.08 (0.70-1.64)		0.723
Yes	1708	0.82 (0.58-1.16)	0.255
No	5186	0.79 (0.61-1.03)	0.084
Alcohol drinking status		1.51 (0.57-4.00)		0.413
Yes	202	1.87 (0.56-6.25)	0.310
No	6674	0.79 (0.64-0.98)	0.032
Smoking status		1.06 (0.80-1.40)		0.865
Yes	918	0.68 (0.40-1.17)	0.165
No	5958	0.82 (0.65-1.03)	0.086
Physical activity		1.04 (0.85-1.266)		0.762
No exercise	3192	0.64 (0.46-0.90)	0.011
Low intensity exercise	2121	1.05 (0.75-1.49)	0.766
Moderate intensity exercise	875	0.79 (0.44-1.41)	0.422
High intensity exercise	688	0.73 (0.36-1.49)	0.390

BMI: Body mass index; CI: Confidence interval; OR: Odds ratio.

Table 5 Sensitivity analysis

	Unadjusted		Model 11		Model 22
	OR (95%CI)	P value	OR (95%CI)	P value	OR (95%CI)	P value
Diabetes	0.50 (0.35-0.71)	< 0.001	0.58 (0.41-0.83)	0.003	0.68 (0.47-0.99)	0.045
High FBG	0.69 (0.48-0.99)	0.041	0.79 (0.55-1.14)	0.212	0.85 (0.58-1.25)	0.408
High 2h-PG	0.72 (0.61-0.84)	< 0.001	0.76 (0.65-0.90)	0.001	0.83 (0.70-0.99)	0.035
High HbA1c	0.59 (0.50-0.69)	< 0.001	0.65 (0.55-0.76)	< 0.001	0.76 (0.64-0.91)	0.002

¹Adjusted for sex, age, and body mass index.

²Further extended model 1 by incorporating adjustments for education level, smoking status, physical activity, alcohol consumption, hypertension, total cholesterol, triglycerides, high- and low-density cholesterol lipoprotein, family history of diabetes. 2h-PG: 2-hour blood glucose; CI: Confidence interval; FBG: Fasting plasma glucose; OR: Odds ratio; HbA1c: Glycated hemoglobin.