Association between fasting glucose and all-cause mortality according to sex and age: a prospective cohort study

Abstract

The association of fasting glucose with the risk of death according to sex and age remains unclear, and insufficient information is available on sex- and age-specific glucose concentrations within ethnic groups. This study analyzed a sample of 12,455,361 Korean adults who participated in health examinations during 2001-2004, and were followed up until 2013. Men had 3.0 mg/dL (0.167 mmol/L) higher mean glucose concentrations than women (94.7 vs. 91.7 mg/dL), although women over 73 years had higher levels. For glucose levels of 100-199 mg/dL, each 18 mg/dL (1 mmol/L) increase in fasting glucose increased mortality by 13% (HR = 1.13, [95% CI 1.12 to 1.13], p < 0.001). In individuals with fasting glucose levels of 100-125 mg/dL, each 18 mg/dL increase in fasting glucose was associated with a 30% increase in the risk for mortality (1.30, [1.18 to 1.43]) in those aged 18-34 years, a 32% increase (1.32, [1.26 to 1.39]) in those aged 35-44 years, and a 10% increase (1.10, [1.02 to 1.19]) in those aged 75-99 years. The fasting glucose levels associated with the lowest mortality were 80-94 mg/dL regardless of sex and age. Prediabetes (100-125 mg/dL) was associated with higher mortality. The associations of hyperglycemia with mortality were stronger at younger ages.

Figure 1

Mean and median concentration of fasting glucose. To convert glucose from mg/dL to mmol/L, multiply by 0.0555.

Figure 2

Hazard ratios^* associated with 16 categories of baseline fasting serum glucose (FSG) for mortality, according to sex. FSG categories (mg/dL: <65, 65–69, 70–74, 75–79, 80–84, 85–90, 90–94 [Reference], 95–99, 100–104, 105–109, 110–117, 118–125, 125–139, 140–169, 170–199, ≥200). The midpoint was used as a representative value for each FSG category, except for both ends (61 and 248), for which the median of all participants was used. *Hazard ratios and 95% confidence intervals were calculated using Cox proportional hazard models stratified by baseline age (years: 18–24, 25–34, 35–44, 45–54, 55–64, 65–74, 75–84, 85–99), after adjustment for age at baseline (continuous variable), sex (if applicable), smoking status, alcohol use, physical activity, body-mass index, systolic blood pressure, and total cholesterol levels. To convert glucose from mg/dL to mmol/L, multiply by 0.0555.

Figure 3

Hazard ratios* for mortality according to age by restricted cubic splines of fasting serum glucose with five knots (70, 85, 100, 120, and 140 mg/dL) and 90 mg/dL as a reference in men (n = 7,043,405) and women (n = 5,356,918) having fasting glucose ≤300 mg/dL. *Hazard ratios and 95% confidence intervals were calculated using the same method as in Fig. 2. To convert glucose from mg/dL to mmol/L, multiply by 0.0555.

Figure 4

Hazard ratios^* per each 18 mg/dL (1 mmol/L) increase in fasting serum glucose (FSG), according to FSG range and age. *Hazard ratios and 95% confidence intervals were calculated using the same method as in Fig. 2. To convert glucose from mg/dL to mmol/L, multiply by 0.0555.