HbA 1c levels in non-diabetic older adults – No J-shaped associations with primary cardiovascular events, cardiovascular and all-cause mortality after adjustment for confounders in a meta-analysis of individual participant data from six cohort studies

Table 5 Age-stratified analyses of the associations of HbA_1c levels with mortality and cardiovascular outcomes in subjects without diabetes mellitus

Outcome/stratum	Very low HbA_1c (<5.0 %) (<31 mmol/mol)				Low HbA_1c (5.0 to <5.5 %) (31 to <37 mmol/mol)				Intermediate HbA_1c (5.5 to <6.0 %) (37 to <42 mmol/mol)				Increased HbA_1c (6.0 to <6.5 %) (42 to <48 mmol/mol)
	n_total	n_cases	IR^a	HR (95 % CI)^b	n_total	n_cases	IR^a	HR	n_total	n_cases	IR^a	HR (95 % CI)^b	n_total	n_cases	IR^a	HR (95 % CI)^b
All-cause mortality
50–64 years	1,688	205	10.0	0.95 (0.81; 1.12)	6,563	769	9.8	Ref	6,336	761	10.1	0.91 (0.82; 1.01)	1,514	272	15.8	1.18 (1.02; 1.37)
≥65 years	632	314	53.3	1.13 (1.01; 1.27)	3,779	1,556	42.6	Ref	4,767	1,978	43.3	1.06 (0.99; 1.13)	1,413	723	50.4	1.14 (1.04; 1.26)
Cardiovascular mortality
50–64 years	1,218	61	3.7	0.99 (0.74; 1.33)	4,824	210	3.2	Ref	4,915	220	3.4	0.93 (0.76; 1.13)	1,194	78	5.3	1.14 (0.87; 1.50)
≥65 years	548	155	28.4	1.33 (0.86; 2.04)^c	2,574	589	20.9	Ref	3,343	753	21.2	1.07 (0.82; 1.39)^c ^d	1,035	249	24.2	1.18 (1.01; 1.38)
Cardiovascular events
50–64 years	1,276	77	5.1	0.76 (0.60; 0.97)	5,626	456	8.1	Ref	5,470	507	9.6	1.09 (0.96; 1.25)	1,165	114	10.6	1.18 (0.95; 1.47)
≥65 years	409	82	22.4	1.15 (0.90; 1.46)	2,491	488	22.8	Ref	3,207	598	23.0	0.99 (0.88; 1.12)	846	171	26.7	1.19 (0.98; 1.45)

Bold indicates statistically significant difference (p <0.05). ^aIR, incidence rate per 1,000 person-years. The IR is the weighted mean of the IRs of the individual studies (weighted by sample size); ^badjusted for age, sex, race/ethnicity, BMI, education, smoking, physical activity, alcohol consumption, total cholesterol, HDL cholesterol, CRP, hemoglobin, serum creatinine, albuminuria, hypertension and history of CVD; ^crandom effects model result reported due to statistical significant heterogeneity. CI, confidence interval; HbA_1c, glycated hemoglobin; HR, hazard ratio; IR, incidence rate; n, sample size