TABLE 5.

Meta-analysis of phospholipid trans-palmitoleic acid and incident diabetes mellitus among 5266 US adults in the MESA and the CHS¹

	Cohort-specific quintiles of trans-palmitoleic acid
	1	2	3	4	5	P-trend2
Person-years of follow-up	8389	6927	7201	8386	7839
No. of incident cases	147	94	86	110	72
Multivariable-adjusted HR (95% CI)3	1.0 (reference)	0.78 (0.58, 1.05)	0.79 (0.58, 1.09)	0.62 (0.46, 0.84)	0.44 (0.31, 0.63)	<0.001

¹Risk estimates in each quintile were combined by using inverse-variance weighted meta-analysis with fixed effects. The I² values for the pooled estimates in quintiles 2–5 were 0%, 0%, 84%, and 0%, respectively. The evidence for heterogeneity in the pooled analysis for quintile 4 (P-heterogeneity = 0.01) was consistent with the HR of 0.41 (95% CI: 0.26, 0.64) in the CHS and 0.89 (95% CI: 0.58, 1.35) in the MESA. As shown in the table, pooling of these study-specific findings resulted in a clear monotonic relation between trans-palmitoleic acid and incident diabetes. Findings using random-effects models were very similar. CHS, Cardiovascular Health Study; GLST, generalized least-squares models for trend; MESA, Multi-Ethnic Study of Atherosclerosis.

²Assessed by using GLST, which uses the multiple data points across quintiles in both cohorts simultaneously to assess dose-response, accounting for the HRs, CIs, and absolute differences in exposure levels across quintiles in each cohort. GLST meta-analysis resulted in a pooled multivariable-adjusted HR of 0.66 (95% CI: 0.56, 0.77) for each 0.05 percentage point of higher trans-palmitoleate concentrations.

³HRs in the MESA were adjusted for age (y), sex, race-ethnicity (white, black, Hispanic, Chinese), education (<high school, high school, some college, college graduate), field center (6 sites), smoking status (never, former, current), alcohol use (drinks/wk), physical activity (metabolic equivalent min/wk), BMI (kg/m²), waist circumference (cm), and dietary consumption of whole-fat dairy foods (servings/wk), low-fat dairy foods (servings/wk), red meat (servings/wk), and total energy (kcal/d). HRs in the CHS were adjusted for age (y), sex, race (white, nonwhite), education (<high school, high school, some college, college graduate), field center (4 sites), smoking status (never, former, current), BMI (kg/m²), waist circumference (cm), coronary heart disease (yes, no), physical activity (kcal/wk), alcohol use (6 categories), and dietary consumption of carbohydrate (% of energy), protein (% of energy), red meat (servings/wk), whole-fat dairy foods (6 categories), low-fat dairy foods (5 categories), and total energy (kcal/d).