Table 2.
Baseline characteristics of participants according to category of melatonin secretion
| Covariates | Category of melatonin secretion† | p-value* (trend) | |||
|---|---|---|---|---|---|
| Lowest (N=292) | Intermediate (N=246) | Highest (N=202) | |||
| Median (5-95% range) | |||||
| Urine aMT6s/creatinine (ng/mg)# | 14.4 (4.2 – 24.8) | 35.4 (27.0 – 47.6) | 67.0 (50.2 – 177.5) | ||
| Urine aMT6s (ng/dL)# | 930 (240 – 2760) | 2340 (1150 – 5730) | 5075 (2080 – 17900) | <0.0001 | |
| Urine creatinine (mg/dL) # | 69.1 (34.7 – 156.1) | 64.3 (34.3 – 162.5) | 68.9 (35.6 – 160.4) | 0.75 | |
| Age (years) | 65.1 (55.7 – 75.7) | 64.3 (56.0 – 74.1) | 63.7 (55.4 – 75.1) | 0.07 | |
| BMI (kg/m2) | 27.8 (20.0 – 39.5) | 27.4 (20.8 – 38.4) | 26.1 (20.5 – 36.0) | 0.003 | |
| Physical activity, (METs/week) ‡ | 12.3 (0.2 – 55.9) | 12.2 (0.3 – 54.9) | 10.6 (0.4 – 57.4) | 0.18 | |
| AHEI Score i | 43.1 (24.5 – 64.0) | 44.3 (26.5 – 62.5) | 44.1 (26.7 – 63.3) | 0.35 | |
| Glycemic index | 53.5 (48.3 – 58.9) | 53.9 (47.3 – 58.5) | 53.5 (46.8 – 58.1) | 0.80 | |
| Polyunsaturated/saturated fat | 0.58 (0.34 – 1.10) | 0.61 (0.35 – 1.02) | 0.58 (0.35 – 1.00) | 0.96 | |
| %energy trans fat | 1.54 (0.72 – 2.55) | 1.51 (0.80 – 2.60) | 1.62 (0.85 – 2.77) | 0.56 | |
| Cereal fiber in diet (gm) | 5.6 (2.7 – 10.8) | 6.0 (2.7 – 11.4) | 5.9 (2.8 – 11.8) | 0.33 | |
| Alcohol consumption (gm/day) | 0.9 (0.0 – 28.6) | 1.5 (0.0 – 26.7) | 0.9 (0.0 – 13.6) | 1.00 | |
| E-selectin (ng/mL) | 38.6 (17.6 – 68.3) | 36.3 (17.8 – 70.7) | 35.9 (16.3 – 60.7) | 0.13 | |
| HsCRP (mg/L) | 3.1 (0.6 – 21.2) | 2.8 (0.5 – 19.6) | 2.5 (0.4 – 18.0) | 0.14 | |
| ICAM-1 (ng/mL) | 271.0 (179.6 – 454.9) | 267.7 (184.8 – 414.4) | 263.8 (178.0 – 374.5) | 0.25 | |
| IL-6 (pg/mL) | 1.5 (0.7 – 5.6) | 1.4 (0.5 – 6.6) | 1.3 (0.5 – 4.4) | 0.005 | |
| Insulin (uU/mL) | 7.2 (2.4 – 28.0) | 6.6 (1.8 – 22.9) | 6.1 (1.9 – 20.9) | 0.009 | |
| Triglyceride (mg/dL) | 146 (71 – 316) | 142 (56 – 273) | 121 (57 – 313) | 0.001 | |
| Insulin sensitivity (McAuley index) | 6.9 (4.4 – 11.2) | 7.4 (4.6 – 11.6) | 7.5 (4.3 – 12.4) | 0.007 | |
| N(%) | |||||
| Control subjects | 123(33) | 124(34) | 123(33) | ||
| Case Subjects | 169(45) | 122(33) | 79(21) | <0.0001 | |
| White race | 281 (96) | 231 (94) | 196 (97) | 0.22 | |
| Smoking history | Current | 11 (4) | 25 (10) | 10 (5) | 0.39 |
| Past | 137 (47) | 109 (44) | 92 (46) | 0.72 | |
| Family history of diabetes | 77 (26) | 65 (26) | 58 (29) | 0.59 | |
| History of HTN | 165 (56) | 119 (48) | 92 (46) | 0.01 | |
| Treatment for HTN | 145 (50) | 108 (44) | 73 (36) | 0.003 | |
| Snoring | Most nights | 73 (25) | 61 (25) | 43 (21) | 0.37 |
| Occasionally | 18 (6) | 18 (7) | 15 (7) | 0.57 | |
| Almost never | 194 (66) | 160 (65) | 138 (68) | 0.71 | |
| Sleep duration (hrs per night) | ≤ 5 | 16 (5) | 10 (4) | 7 (3) | 0.27 |
| 6 | 60 (21) | 47 (19) | 40 (20) | 0.81 | |
| 7-8 | 192 (66) | 163 (66) | 145 (72) | 0.18 | |
| 9 | 14 (5) | 20 (8) | 6(3) | 0.52 | |
| ≥10 | 6(2) | 2 (1) | 1 (1) | 0.14 | |
| Region of the US!! | North | 148 (51) | 128 (52) | 103 (51) | 0.92 |
| South | 49 (17) | 39 (16) | 31 (15) | 0.66 | |
| Mid-west | 74 (25) | 56 (23) | 47 (23) | 0.56 | |
| West | 21 (7) | 23 (9) | 21 (10) | 0.20 | |
| NSAID use | 84(29) | 73 (30) | 64 (32) | 0.78 | |
| Beta-blocker use | 67 (23) | 47 (19) | 23 (11) | 0.005 | |
| Post-menopausal | 288 (99) | 242 (98) | 198 (98) | 0.87 | |
Melatonin secretion was assessed by measuring the urinary appearance of its primary metabolite (6-sulfatoxymelatonin [aMT6s]) in the first morning urine with normalization using urinary creatinine.
p-values for trend across categories of melatonin secretion were calculated using univariate median regression for continuous variables and the Cochran-Armitage trend test for categorical values.
aMT6s, aMT6s/creatinine and creatinine are displayed without log-transformation. In later analyses, aMT6s/creatinine is log-transformed when used as a continuous variable.
Physical activity (METs/week) sum of the average time/week spent in each activity × MET value of each activity. METs measure the ratio of the work metabolic rate to the resting metabolic rate.
AHEI is a diet-quality score that reflects a common dietary pattern associated with a lower risk of type 2 diabetes.
North region includes PA, NY, NJ, CT, RI, MA, NH, VT, and ME. South region includes OK, TX, LA, AR, MS, AL, FL, GA, SC, NC, VA, TN, KY, WV, DC, MD, and DE. Midwest region includes ND, SD, NE, KS, MN, IA, MO, WI, IL, MI, IN and OH. West region includes WA, OR MT, ID, WY, CA, NV, UT, CO, AZ, and NM.
Abbreviations: AHEI, alternative healthy eating index; hsCRP, high sensitivity c-reactive protein; ICAM-1, intercellular adhesion molecule-1; IL-6, interleukin 6; HTN, hypertension; METs, metabolic equivalent of task.