Caffeinated and Decaffeinated Coffee Consumption and Risk of Type 2 Diabetes

A Systematic Review and a Dose-Response Meta-analysis

Ming Ding; Shilpa N. Bhupathiraju; Mu Chen; Rob M. van Dam; Frank B. Hu

Diabetes Care. 2014;37(2):569-586.

Abstract and Introduction

Abstract

Objective Previous meta-analyses identified an inverse association of coffee consumption with the risk of type 2 diabetes. However, an updated meta-analysis is needed because new studies comparing the trends of association for caffeinated and decaffeinated coffee have since been published.

Research design and methods PubMed and Embase were searched for cohort or nested case-control studies that assessed the relationship of coffee consumption and risk of type 2 diabetes from 1966 to February 2013. A restricted cubic spline random-effects model was used.

Results Twenty-eight prospective studies were included in the analysis, with 1,109,272 study participants and 45,335 cases of type 2 diabetes. The follow-up duration ranged from 10 months to 20 years. Compared with no or rare coffee consumption, the relative risk (RR; 95% CI) for diabetes was 0.92 (0.90–0.94), 0.85 (0.82–0.88), 0.79 (0.75–0.83), 0.75 (0.71–0.80), 0.71 (0.65–0.76), and 0.67 (0.61–0.74) for 1–6 cups/day, respectively. The RR of diabetes for a 1 cup/day increase was 0.91 (0.89–0.94) for caffeinated coffee consumption and 0.94 (0.91–0.98) for decaffeinated coffee consumption (P for difference = 0.17).

Conclusions Coffee consumption was inversely associated with the risk of type 2 diabetes in a dose-response manner. Both caffeinated and decaffeinated coffee was associated with reduced diabetes risk.

Introduction

Type 2 diabetes is a chronic disease with high rates of morbidity and mortality. The worldwide prevalence of type 2 diabetes is increasing, and the global number of people with diabetes is estimated to reach 366 million by the year 2030.^[1] The risk of blindness, renal disease, and amputation among those with type 2 diabetes is 20 to 40 times higher than that of people without diabetes. Furthermore, those with type 2 diabetes have a two to five times higher risk of myocardial infarction and two to three times higher risk of stroke.^[2] Given its significant burden, identifying modifiable lifestyle factors is imperative for the prevention of diabetes.

Coffee is one of the most widely consumed beverages around the world; thus, investigating its association with various diseases has important public health implications. An inverse association between coffee consumption and risk of type 2 diabetes was first reported in a Dutch population.^[3] In subsequent years, this finding has been confirmed in most^[4–10] but not all^[11–13] studies. Two previous meta-analyses of coffee consumption and risk of type 2 diabetes have been published. van Dam and Hu^[14] included nine cohort studies and reported a lower risk of type 2 diabetes for high coffee consumption compared with no coffee consumption with little between-study heterogeneity. Huxley et al.^[15] included 18 prospective studies and found an inverse monotonous association between the number of cups of coffee consumed and diabetes risk, but they double-counted data from the same cohort.^[16,17] Since the publication of these meta-analyses, 10 additional prospective studies on the association between coffee consumption and diabetes have been published.^{[6,8,10,12,18–23]}

A key issue that remains to be resolved is whether consumption of caffeinated and decaffeinated coffee is similarly associated with the risk of type 2 diabetes. Such results would provide insight into the role of caffeine in the putative relationship between coffee consumption and diabetes risk. The meta-analysis by Huxley et al.^[15] included only six studies on decaffeinated coffee, and estimates were less precise than for caffeinated coffee because of lower consumption levels. Eight subsequent prospective studies evaluated the association with decaffeinated coffee, approximately doubling the amount of data on decaffeinated coffee and diabetes risk.^{[8,10,12,18–21,24]} We therefore performed an updated systematic review and a dose-response meta-analysis of all available data on the association of both caffeinated and decaffeinated coffee consumption with the risk of type 2 diabetes.

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Next Section

Table 1. Basic characteristics of the included studies
Authors	Country	Sex	Age at baseline (year)	Follow-up (year)	N	n	Type 2 diabetes assessment	Coffee exposure (cups/day)	RR (95% CI)	Confounding adjustments	NOS (0–9 points)
van Dam and Feskens 2002 (3)	Europe	Both	30–60	1–13	17,111	306	Self-reported	Total coffee		Educational level, leisure time physical activity, occupational physical activity, alcohol consumption, cigarette smoking, history of cardiovascular disease, known hypertension, and known hypercholesterolemia	6
								≤2	1.00 (1.00–1.00)
								3–4	0.79 (0.57–1.10)
								5–6	0.73 (0.53–1.01)
								≥7	0.50 (0.35–0.72)
Reunanen et al. 2003 (11)	Europe	Both	20–98	304,227^a	19,518	855	Confirmed cases	Total coffee		Age, sex, BMI, smoking, and leisure time physical activity	8
								≤2	1.00 (1.00–1.00)
								3–4	1.01 (0.81–1.27)
								5–6	0.98 (0.79–1.21)
								≥7	0.92 (0.73–1.16)
Carlsson et al. 2004 (7)	Europe	Both	30–60	20	10,652	408	Confirmed cases	Total coffee		Age, sex, BMI, education, leisure time physical activity, alcohol consumption, and smoking	6
								≤2	1.00 (1.00–1.00)
								3–4	0.70 (0.48–1.01)
								5–6	0.71 (0.50–1.01)
								≥7	0.65 (0.44–0.96)
Rosengren et al. 2004 (27)	Europe	F	39–65	18	1,361	74	Confirmed cases	Total coffee		Age, smoking, low physical activity, education, BMI, and serum cholesterol and triglycerides	8
								≤2	1.00 (1.00–1.00)
								3–4	0.56 (0.32–0.98)
								5–6	0.45 (0.23–0.90)
								>6	0.57 (0.26–1.29)
Salazar-Martinez et al. 2004 (4)	U.S.	Both	M 40–75	M 12	41,934	1,333	Confirmed self-report	Caffeine (men)^b		Age; total caloric intake; family history of diabetes; alcohol consumption; smoking status; menopausal status and postmenopausal hormone use; intakes of glycemic load, trans fat, polyunsaturated fatty acid, cereal fiber, and magnesium; BMI; and physical activity	6
			F 30–55	F 18				13	1.00 (1.00–1.00)
								74	1.06 (0.89–1.26)
								172	1. 01 (0.85–1.20)
								323	0.94 (0.78–1.12)
								566	0.80 (0.66–0.97)
					M 84,276			Caffeine (women)^b
					F 4,085			69	1.00 (1.00–1.00)
								193	1.02 (0.93–1.11)
								328	0.90 (0.82–0.99)
								432	0.85 (0.77–0.94)
								708	0.70 (0.63–0.79)
van Dam et al. 2004 (28)	Europe	Both	50–74	6.4	1,312	128	OGTT	Total coffee		Age; sex; BMI; waist-hip ratio; physical activity; alcohol consumption; cigarette smoking; history of cardiovascular disease; use of antihypertensive medication; and intake of fiber, total energy, saturated fat, and polyunsaturated fat	8
								≤2	1.00 (1.00–1.00)
								3–4	0.94 (0.56–1.55)
								5–6	0.92 (0.53–1.61)
								≥7	0.69 (0.31–1.51)
Greenberg et al. 2005 (35)	U.S.	Both	32–88	8.4	7,006	170	Self-reported	Caffeinated coffee		Per capita income, educational level, race, sex, physical activity, smoking status, alcohol consumption, BMI, age, and type of diet; variables for consumption of caffeine and all three beverages were in the regression model simultaneously	6
								0	1.00 (1.00–1.00)
								<2	0.82 (0.55–1.23)
								24	0.75 (0.50–1.13)
								≥4	0.37 (0.22–0.64)
								Decaf. coffee
								0	1.00 (1.00–1.00)
								<2	0.62 (0.34–1.11)
								2–4	0.43 (0.20–0.93)
								Caffeine^b
								75	1.00 (1.00–1.00)
								225	0.69 (0.42–1.11)
								375	0.73 (0.38–1.41)
								525	0.65 (0.30–1.42)
								750	0.65 (0.24–1.77)
Iso et al. 2006 (9)	Asia	Both	40–65	5	17,413	444	Self-reported	Total coffee		Family history of diabetes, smoking status, alcohol intake, magnesium intake, hours of walking, hours of exercise, and consumption of other beverages	6
								<2	0.82 (0.55–1.23)
								2–4	0.75 (0.50–1.13)
								≥4	0.37 (0.22–0.64)
								≥3	0.58 (0.37–0.90)
								Caffeine^b
								57	1.00 (1.00–1.00)
								137	1.00 (0.73–1.37)
								199	0.98 (0.73–1.33)
								273	1.00 (0.74–1.37)
								416	0.67 (0.47–0.95)
Paynter et al. 2006 (29)	U.S.	Both	45–64	9	12,204	1,437	Self-reported	Total coffee (men)		Age, race, education, family history of diabetes, BMI, waisthip ratio, total caloric intake, dietary fiber, smoking, alcohol consumption, leisure activity, and hypertension	8
								0	1.00 (1.00–1.00)
								<1	1.02 (0.76–1.38)
								1	1.01 (0.76–1.34)
								2–3	0.93 (0.70–1.22)
								≥4	0.69 (0.50–0.96)
								Total coffee (women)
								0	1.00 (1.00–1.00)
								<1	1.23 (0.93–1.62)
								1	1.06 (0.83–1.36)
								2–3	0.89 (0.68–1.16)
								≥4	0.66 (0.45–0.96)
Pereira et al. 2006 (13)	U.S.	F	Mean 61	11	28,812	1,418	Self-reported	Total coffee		Age, education, baseline hypertension, alcohol, smoking status, cigarette pack-years, BMI, waist-hip ratio, physical activity, energy intake, total fat, Keys score, cereal fiber, tea consumption, and soda consumption	6
								0	1.00 (1.00–1.00)
								<1	0.95 (0.77–1.18)
								1–3	1.01 (0.85–1.19)
								4–5	0.85 (0.69–1.04)
								≥6	0.79 (0.61–1.02)
								Caffeinated coffee
								0	1.00 (1.00–1.00)
								<1	0.92 (0.76–1.11)
								1–3	0.88 (0.70–1.12)
								4–5	0.89 (0.64–1.23)
								≥6	1.00 (0.84–1.19)
								Decaf. coffee
								0	1.00 (1.00–1.00)
								<1	0.98 (0.83–1.16)
								1–3	1.01 (0.84–1.21)
								4–5	0.59 (0.44–0.80)
								≥6	0.68 (0.43–1.09)
van Dam et al. 2006 (5)	U.S.	F	26–46	20	88,259	1,263	Self-reported	Total coffee		Age; smoking status; BMI; physical activity; alcohol consumption; use of hormone replacement therapy; oral contraceptive use; family history of type 2 diabetes; history of hypertension; history of hypercholesterolemia; consumption of sugarsweetened soft drinks; consumption of punch; and quintiles of processed meat consumption, the polyunsaturated-tosaturated fat intake ratio, total energy intake, the glycemic index, and cereal fiber intake	5
								0	1.00 (1.00–1.00)
								<1	0.93 (0.80–1.09)
								1	0.87 (0.73–1.03)
								2–3	0.58 (0.49–0.68)
								≥4	0.53 (0.41–0.68)
								Caffeinated coffee
								0	1.00 (1.00–1.00)
								<1	1.00 (0.86–1.17)
								1	0.89 (0.75–1.07)
								2–3	0.62 (0.52–0.74)
								≥4	0.61 (0.46–0.81)
								Decaf. coffee
								0	1.00 (1.00–1.00)
								<1	0.86 (0.74–0.99)
								1	0.87 (0.68–1.11)
								2–3	0.52 (0.36–0.74)
								Caffeine^b
								22	1.00 (1.00–1.00)
								93	0.88 (0.75–1.04)
								180	0.89 (0.75–1.05)
								341	0.74 (0.62–0.89)
								528	0.55 (0.45–0.67)
Smith et al. 2006 (30)	U.S.	Both	≥50	8	910	84	OGTT	Total coffee		Sex, age, physical activity, BMI, smoking, alcohol, hypertension, and baseline fasting plasma glucose	7
								0	1.00 (1.00–1.00)
								1–2	0.66 (0.38–1.14)
								3–4	0.53 (0.26–1.08)
								≥5	0.60 (0.26–1.40)
Adeney et al. 2007 (24)	U.S.	F	Mean 31	10 mo	1,744	75	OGTT	Caffeinated coffee		Maternal age, smoking during pregnancy, regular alcohol use before pregnancy, maternal race, prepregnancy BMI, chronic hypertension, and average daily caloric intake	6
								None	1.00 (1.00–1.00)
								Moderate	0.58 (0.33–1.02)
								High	0.76 (0.40–1.46)
Fuhrman et al. 2009 (31)	U.S.	M	35–79	2.6	4,685	519	OGTT	Total coffee^c		Age, BMI, smoking status, family history of diabetes, education, alcohol intake, index of physical activity, and milk and sugar intake	7
								1–2	1.00 (1.00–1.00)
								3	0.79 (0.69–1.00)
								≥4	0.75 (0.58–0.97)
Hamer et al. 2008 (32)	Europe	Both	35–55	11.7	5,823	387	OGTT	Total coffee		Five-year age categories, sex, ethnicity, employment grade, plus BMI category, waist-hip ratio, smoking, sex-specific alcohol intake tertiles, physical activity category, family history of diabetes, hypertension, cholesterol, total energy intake, diet pattern, and mutual adjustment for all beverage type	8
								0	1.00 (1.00–1.00)
								≤1	0.83 (0.60–1.14)
								2–3	0.85 (0.60–1.20)
								>3	0.80 (0.54–1.18)
								Decaf. coffee
								0	1.00 (1.00–1.00)
								≤1	1.13 (0.87–1.47)
								2–3	0.87 (0.58–1.30)
						;		>3	0.65 (0.36–1.16)
Odegaard et al. 2008 (33)	Asia	Both	45–74	5.7	36,908	1,889	Confirmed self-report	Total coffee		Age at recruitment, year of interview, sex, dialect, education, hypertension, smoking status, alcohol consumption, BMI, physical activity, dietary variables, and magnesium	9
								<1	1.00 (1.00–1.00)
								1	0.94 (0.81–1.09)
								2–3	0.83 (0.68–1.01)
								≥4	0.70 (0.53–0.93)
Bidel et al. 2008 (17)	Europe	Both	35–74	5–20	21,826	862	Confirmed cases	Total coffee		Age, BMI, alcohol consumption, smoking, physical activity, and glucose tolerance test	7
								0–2	1.00 (1.00–1.00)
								3–4	0.85 (0.70–1.04)
								5–6	0.78 (0.65–0.95)
								≥7	0.64 (0.51–0.80)
Kato et al. 2009 (34)	Asia	Both	40–69	10	55,826	2,694	Confirmed self-report	Total coffee (men)		Age, BMI, smoking status, alcohol drinking, family history of diabetes, physical activity, history of hypertension, perceived mental stress, levels of type A behavior, and hours of sleep	8
								0	1.00 (1.00–1.00)
								1–2^d	0.93 (0.80–1.08)
								3–4^d	0.84 (0.71–1.01)
								1–2	0.84 (0.73–0.97)
								3–4	0.83 (0.68–1.02)
								≥5	0.82 (0.60–1.11)
								Total coffee (women)
								0	1.00 (1.00–1.00)
								1–2^d	0.90 (0.76–1.06)
								3–4^d	0.95 (0.77–1.17)
								1–2	0.81 (0.69–0.96)
								3–4	0.62 (0.45–0.84)
								≥5	0.40 (0.20–0.78)
Oba et al. 2010 (10)	Asia	Both	<70	10	13,540	453	Self-reported	Caffeinated coffee (men)		Age, smoking status, BMI, physical activity, length of education in years, alcohol consumption, total energy intake, fat intake, and women's menopausal status to examine beverage and chocolate snacks	6
								0	1.00 (1.00–1.00)
								1/mo to 6/wk	0.69 (0.50–0.97)
								≥1	0.69 (0.49–0.98)
								Caffeinated coffee (women)
								0	1.00 (1.00–1.00)
								1/mo to 6/wk	1.08 (0.74–1.60)
								≥1	0.70 (0.44–1.12)
								Decaf. coffee (men)
								0	1.00 (1.00–1.00)
								≥1^e	1.09 (0.73–1.61)
								Decaf. coffee (women)
								0	1.00 (1.00–1.00)
								≥1^e	0.66 (0.36–1.23)
								Caffeine (men)^b
								42	1.00 (1.00–1.00)
								79	0.81 (0.60–1.10)
								218	0.95 (0.69–1.30)
								Caffeine (women)^b
								60	1.00 (1.00–1.00)
								97	1.26 (0.88–1.82)
								226	0.95 (0.63–1.43)
Zhang et al. 2011 (23)	U.S.	Both	45–74	7.6	1,141	188	OGTT	Total coffee		Age, sex, smoking, alcohol use, family history of diabetes, physical activity, and BMI	7
								0	1.00 (1.00–1.00)
								1–2	0.93 (0.55–1.57)
								3–4	0.87 (0.53–1.44)
								5–7	0.72 (0.43–1.23)
								8–11	0.78 (0.44–1.37)
								≥12	0.33 (0.13–0.81)
van Dieren et al. 2009 (22)	Europe	Both	49–70	10	40,011	918	Confirmed self-report	Total coffee		Cohort, sex, age, BMI, highest education, physical activity, family history of diabetes, smoking, alcohol intake, energy intake, energy-adjusted saturated fat intake, energy-adjusted fiber intake, energyadjusted vitamin C intake, hypercholesterolemia, and hypertension	6
								0–1	1.00 (1.00–1.00)
								1–2	0.88 (0.69–1.11)
								2–3	0.94 (0.75–1.17)
								3–4	0.75 (0.60–0.92)
								4–6	0.74 (0.61–0.91)
								>6	0.84 (0.65–1.08)
Boggs et al. 2010 (21)	U.S.	F	30–69	12	46,906	3,671	Self-reported	Caffeinated coffee		Age, questionnaire cycle, energy intake, education, family history of diabetes, vigorous activity, smoking, glycemic index, cereal fiber, sugar-sweetened soft drinks, BMI, history of hypertension, and history of high cholesterol	6
								0^e	1.00 (1.00–1.00)
								1 cup/mo to
								<1 cup/day	0.94 (0.86–1.04)
								1	0.90 (0.81–1.01)
								2–3	0.82 (0.72–0.93)
								≥4	0.83 (0.69–1.01)
								Decaf. coffee
								0^e	1.00 (1.00–1.00)
								1 cup/mo to
								<1 cup/day	1.04 (0.93–1.16)
								1	1.07 (0.92–1.25)
								2–3	1.01 (0.83–1.24)
								≥4	1.10 (0.81–1.49
Sartorelli et al. 2010 (20)	Europe	F	41–72	11	69,532	1,415	Confirmed self-report	Total coffee		Age, history of diabetes in ascendants, quartiles of physical activity level, quartiles of alcohol intake, educational level, hypercholesterolemia, hypertension, smoking, energyadjusted fiber and saturated fat, total energy without alcohol, menopausal status, hormone replacement therapy as a time-dependent variable, use of oral contraceptives at baseline, and timedependent BMI	7
								0	1.00 (1.00–1.00)
								≤1	1.04 (0.87–1.26)
								1.1–2.9	0.86 (0.73–1.02)
								≥3	0.73 (0.61–0.87)
								Caffeinated coffee
								0	1.00 (1.00–1.00)
								≤1	0.85 (0.74–0.97)
								>1	0.67 (0.57–0.78)
								Decaf. coffee
								0	1.00 (1.00–1.00)
								≤1	0.69 (0.51–0.93)
								>1	0.67 (0.47–0.95)
								Caffeine^b
								48	1.00 (1.00–1.00)
								126	0.84 (0.72–0.96)
								209	0.77 (0.66–0.89)
								397	0.67 (0.58–0.78)
Goto et al. 2011 (12)	U.S.	F	Mean 60	10	718	359	Confirmed self-report	Caffeinated coffee		Age, race, duration of follow-up, time of blood draw, smoking status, physical activity, family history of diabetes, alcohol use, total calories, and BMI	7
								0	1.00 (1.00–1.00)
								≤1	0.92 (0.46–1.84)
								2–3	0.96 (0.48–1.94)
								≥4	0.71 (0.31–1.61)
								Decaf. coffee
								0	1.00 (1.00–1.00)
								≤1	1.31 (0.84–2.03)
								2–3	0.91 (0.42–2.00)
								≥4	0.92 (0.26–3.27)
								Caffeine^b
								13	1.00 (1.00–1.00)
								140	1.53 (0.71–3.30)
								366	1.70 (0.79–3.62)
								656	1.32 (0.61–2.82)
Hjellvik et al. 2011 (6)	Europe	Both	40–45	5–20	362,045	9,886	Confirmed cases	Total coffee		Year of birth and, where relevant, sex, BMI, smoking, education, and physical activity	7
								<1	1.00 (1.00–1.00)
								1–4	0.84 (0.79–0.89)
								5–8	0.65 (0.61–0.70)
								>9	0.63 (0.58–0.69)
Floegel et al. 2012 (8)	Europe	Both	35–65	8.9	42,659	1,432	Confirmed self-report	Caffeinated coffee		Age, center, sex, smoking, alcohol intake, physical activity, education, employment, vitamin andmineral supplement use during past 4 wk, total energy intake, tea intake, decaf. coffee intake, BMI, waist-hip ratio, and prevalent hypertension	7
								<1	1.00 (1.00–1.00)
								1–2	0.89 (0.69–1.16)
								2–3	0.92 (0.76–1.13)
								3–4	0.82 (0.65–1.02)
								≥4	0.77 (0.63–0.94)
								Decaf. coffee
								<1	1.00 (1.00–1.00)
								1–2	0.97 (0.68–1.39)
								2–3	1.11 (0.84–1.48)
								3–4	0.70 (0.41–1.19)
								≥4	0.70 (0.46–1.06)
Bhupathiraju et al. 2013 (19)	U.S.	Both	M 40–75 F 30–55	M 22 F 24	39,059	2,865	Confirmed self-report	Caffeinated coffee (men)		Age; total caloric intake; family history of diabetes; alcohol consumption; smoking status; menopausal status; postmenopausal hormone use; intake of glycemic load, trans fat, polyunsaturated fatty acid, cereal fiber, and magnesium; BMI; and physical activity	6
								<1	1.00 (1.00–1.00)
								1–3	0.95 (0.88–1.03)
								4–5	0.92 (0.82–1.05)
								≥6	0.65 (0.49–0.85)
								Caffeinated coffee (women)
								<1	1.00 (1.00–1.00)
								1–3	0.91 (0.86–0.95)
								4–5	0.78 (0.72–0.85)
								≥6	0.65 (0.58–0.73)
					M 74,749 F 7,370			Decaf. coffee (men)
								0	1.00 (1.00–1.00)
								<1	0.92 (0.84–1.01)
								1–3	0.84 (0.75–0.93)
								≥4	0.84 (0.68–1.03)
								Decaf. coffee (women)
								0	1.00 (1.00–1.00)
								<1	0.95 (0.89–1.00)
								1–3	0.86 (0.81–0.92)
								≥4	0.73 (0.64–0.84
Doo et al. 2013 (18)	U.S.	Both	45–75	14	75,140	8,582	Confirmed cases	Total coffee (men)		Age and adjusted for ethnicity, BMI, physical activity, education, history of hypertension, energy, alcohol intake, smoking status, sugared sodas, dietary fiber per 4,184 kJ, and processed meat per 4,184 kJ	9
								0	1.00 (1.00–1.00)
								<1	1.12 (1.01–1.24)
								1	1.06 (0.97–1.17)
								2	1.05 (0.95–1.16)
								≥3	0.95 (0.84–1.08)
								Total coffee (women)
								0	1.00 (1.00–1.00)
								<1	1.08 (0.98–1.19)
								1	0.96 (0.87–1.05)
								2	0.82 (0.74–0.91)
								≥3	0.69 (0.59–0.81)
								Caffeinated coffee (men)
								0	1.00 (1.00–1.00)
								<1	1.07 (0.98–1.18)
								1	1.02 (0.93–1.11)
								2	0.99 (0.91–1.09)
								≥3	0.86 (0.75–0.98)
								Caffeinated coffee (women)
								0	1.00 (1.00–1.00)
								<1	1.02 (0.94–1.12)
								1	0.93 (0.86–1.01)
								2	0.75 (0.68–0.83)
								≥3	0.65 (0.54–0.78)
								Decaf. coffee (men)
								0	1.00 (1.00–1.00)
								<1	1.08 (1.00–1.16)
								1	1.03 (0.93–1.15)
								≥2	1.07 (0.93–1.23)
								Decaf. coffee (women)
								0	1.00 (1.00–1.00)
								<1	1.07 (0.99–1.15)
								1	1.03 (0.92–1.14)
								≥2	0.85 (0.72–1.01)

Decaf., decaffeinated; F, female; M, male; mo, month; OGGT, oral glucose tolerance test; wk, week. ^aIn person-years. ^bIn mg/day. ^cIn servings/day. ^dIn cups/week. ^eIn cups/month.

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Caffeinated and Decaffeinated Coffee Consumption and Risk of Type 2 Diabetes

A Systematic Review and a Dose-Response Meta-analysis

Abstract and Introduction

Abstract

Introduction

Tables

References

Authors and Disclosures

Authors and Disclosures

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