
, Kyung Hee Kim2, Young Lee3, Yoon-Ju Song4, Joon Ho Moon2,5, Sung Hee Choi2,5, Tae Jung Oh2,5
1Department of Internal Medicine, Veterans Health Service Medical Center, Seoul, Korea
2Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Korea
3Veterans Medical Research Institute, Veterans Health Service Medical Center, Seoul, Korea
4Department of Food Science and Nutrition, The Catholic University of Korea, Bucheon, Korea
5Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea
Copyright © 2026 Korean Endocrine Society
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
CONFLICTS OF INTEREST
No potential conflict of interest relevant to this article was reported.
ACKNOWLEDGMENTS
Tae Jung Oh was supported by an investigator grant from the Seoul National University Bundang Hospital Research Fund (18-2018-0015).
We would like to thank Ms. Nam Yeon Seo, a registered dietitian at the affiliated hospital, for her valuable advice and support during the early phase of this study.
We acknowledge Ji-hyung Kook’s initial efforts in planning the research.
AUTHOR CONTRIBUTIONS
Conception or design: T.J.O. Acquisition, analysis, or interpretation of data: H.A.K., K.H.K., Y.L., Y.J.S., J.H.M., S.H.C., T.J.O. Drafting the work or revising: H.A.K., T.J.O. Final approval of the manuscript: H.A.K., K.H.K., Y.L., Y.J.S., J.H.M., S.H.C., T.J.O.
Values are expressed as mean±standard deviation or number (%). P values represent the results of the one-way analysis of variance (ANOVA), Kruskal-Wallis test, or chi-squared test.
T1DM, type 1 diabetes mellitus; DM, diabetes mellitus; BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; FPG, fasting plasma glucose; PP2, 2-hour postprandial glucose; HbA1c, hemoglobin A1c; eGFR, estimated glomerular filtration rate; MDRD, Modification of Diet in Renal Disease; AST, aspartate transferase; ALT, alkaline transferase; TG, triglyceride; HDL, high density lipoprotein; LDL, low density lipoprotein.
| Variable | Cluster 1 (well-controlled) | Cluster 2 (high variability) | Cluster 3 (high mean glucose) | P value |
|---|---|---|---|---|
| Mean glucose, mg/dL | 138.1±16.8a | 168.3±22.6b | 203.4±40.5c | <0.001 |
| CV, % | 15.4±5.6a | 27.3±5.4b | 17.7±4.3a | <0.001 |
| SD, mg/dL | 21.0±7.4a | 46.1±11.5b | 35.3±7.4c | <0.001 |
| TAR (>250 mg/dL), % | 0.0±0.0 | 7.0±12.6 | 15.8±31.7 | 0.057 |
| TAR (>180 mg/dL), % | 5.5±7.0a | 30.7±9.8b | 51.6±20.7b | <0.001 |
| TIR (70–180 mg/dL), % | 94.5±7.0a | 61.2±14.2b | 32.6±18.1c | <0.001 |
| TBR (<70 mg/dL), % | 0 | 1 (7.1) | 0 | 0.999 |
Values are expressed as mean±standard deviation or number (%). P values represent the results of one-way analysis of variance (ANOVA) or the Kruskal-Wallis test.
CV, coefficient of variation; SD, standard deviation; TAR, time above range; TIR, time in range; TBR, time below range.
a,b,c Post hoc analysis was done for variables with P<0.05 by the Tukey’s honest significant difference test or the Dunn’s test.
Values are expressed as mean±standard deviation. P values within each group represent the results of one-way analysis of variance (ANOVA) or the Kruskal-Wallis test. Day-to-day fluctuations in energy (kcal) and macronutrient intake were defined as the CV (%) or SD (kcal) of daily intake from day 2 to 6 for each individual.
CV, coefficient of variation; SD, standard deviation.
| Variable | Breakfast, % kcal | Lunch, % kcal | Dinner, % kcal | Mean energy intake per meal |
|---|---|---|---|---|
| Total daily energy (CV), % | –0.17 | 0.49a | –0.10 | –0.47a |
| Carbohydrate (CV), % | –0.21 | 0.21 | –0.24 | –0.62a |
| Protein (CV), % | 0.18 | 0.18 | –0.24 | –0.32 |
| Fat (CV), % | 0.21 | 0.31 | –0.32 | –0.42a |
| Total daily energy (SD), kcal | –0.36a | 0.52a | –0.18 | –0.17 |
| Carbohydrate (SD), kcal | –0.16 | 0.06 | –0.32 | –0.43a |
| Protein (SD), kcal | 0.15 | 0.15 | –0.21 | 0.11 |
| Fat (SD), kcal | 0.04 | 0.39a | –0.27 | –0.04 |
| Characteristic | Cluster 1 | Cluster 2 | Cluster 3 | P value |
|---|---|---|---|---|
| Sex, male:female | 3:7 | 6:8 | 5:3 | 0.444 |
| Age, yr | 46.2±17.5 | 50.3±8.8 | 51.0±14.3 | 0.693 |
| T1DM, % | 30.0 | 35.7 | 25.0 | >0.999 |
| DM duration, yr | 11.8±10.2 | 14.6±7.5 | 12.7±9.1 | 0.728 |
| BMI, kg/m2 | 25.6±5.7 | 24.9±6.0 | 28.1±4.8 | 0.202 |
| Obesity | 4 (40.0) | 5 (35.7) | 7 (87.5) | 0.060 |
| SBP, mm Hg | 126.8±11.0 | 126.9±14.0 | 135.1±12.6 | 0.304 |
| DBP, mm Hg | 71.9±4.7 | 71.9±11.6 | 77.6±9.9 | 0.354 |
| FPG, mg/dL | 123.8±41.6 | 141.5±47.5 | 136.4±62.0 | 0.764 |
| PP2, mg/dL | 169.1±82.8 | 203.2±71.6 | 286.7±52.0 | 0.023 |
| HbA1c, % | 8.5±1.2 | 8.7±0.8 | 8.2±1.1 | 0.529 |
| C-peptide, ng/mL | 2.3±2.2 | 1.8±2.5 | 2.4±1.4 | 0.293 |
| Insulin, μIU/mL | 5.3±4.0 | 6.3±7.1 | 12.6±18.8 | 0.167 |
| eGFR MDRD, mL/min/1.73 m2 | 107.3±52.1 | 87.5±24.5 | 90.2±37.4 | 0.437 |
| AST, IU/L | 26.2±5.1 | 25.4±7.6 | 26.0±7.5 | 0.953 |
| ALT, IU/L | 22.6±10.4 | 24.4±9.4 | 27.6±10.8 | 0.577 |
| Total cholesterol, mg/dL | 193.3±53.6 | 157.5±55.4 | 166.5±32.7 | 0.242 |
| TG, mg/dL | 110.2±41.8 | 99.4±48.5 | 180.6±88.0 | 0.013 |
| HDL cholesterol, mg/dL | 60.6±10.8 | 51.5±19.3 | 48.9±12.9 | 0.267 |
| LDL cholesterol, mg/dL | 119.2±38.9 | 92.2±33.8 | 97.8±24.5 | 0.157 |
| Comorbidities | ||||
| Hypertension | 5 (50.0) | 6 (42.9) | 6 (75.0) | 0.357 |
| Dyslipidemia | 7 (70.0) | 12 (85.7) | 7 (87.5) | 0.616 |
| Insulin use | 0.928 | |||
| None | 1 (10.0) | 1 (7.1) | 1 (12.5) | |
| Basal insulin | 0 | 0 | 1 (12.5) | |
| Premixed insulin | 3 (30.0) | 5 (35.7) | 2 (25.0) | |
| Basal bolus insulin | 6 (60.0) | 8 (57.1) | 4 (50.0) |
| Variable | Cluster 1 (well-controlled) | Cluster 2 (high variability) | Cluster 3 (high mean glucose) | P value |
|---|---|---|---|---|
| Mean glucose, mg/dL | 138.1±16.8 |
168.3±22.6 |
203.4±40.5 |
<0.001 |
| CV, % | 15.4±5.6 |
27.3±5.4 |
17.7±4.3 |
<0.001 |
| SD, mg/dL | 21.0±7.4 |
46.1±11.5 |
35.3±7.4 |
<0.001 |
| TAR (>250 mg/dL), % | 0.0±0.0 | 7.0±12.6 | 15.8±31.7 | 0.057 |
| TAR (>180 mg/dL), % | 5.5±7.0 |
30.7±9.8 |
51.6±20.7 |
<0.001 |
| TIR (70–180 mg/dL), % | 94.5±7.0 |
61.2±14.2 |
32.6±18.1 |
<0.001 |
| TBR (<70 mg/dL), % | 0 | 1 (7.1) | 0 | 0.999 |
| Variable | Cluster 1 | Cluster 2 | Cluster 3 | P value |
|---|---|---|---|---|
| Total daily energy, kcal | 2,414.4±316.3 | 2,525.4±494.1 | 2,362.9±735.4 | 0.756 |
| Breakfast, kcal | 548.7±175.2 | 584.9±215.9 | 596.4±253.0 | 0.879 |
| Lunch, kcal | 812.3±176.5 | 766.3±210.6 | 724.9±244.3 | 0.680 |
| Dinner, kcal | 786.7±156.2 | 841.6±198.5 | 715.5±199.8 | 0.325 |
| Snack, kcal | 264.7±228.6 | 332.7±286.3 | 258.2±236.1 | 0.764 |
| Breakfast, % kcal | 22.4±7.7 | 23.1±8.1 | 26.1±10.2 | 0.458 |
| Lunch, % kcal | 35.1±8.3 | 30.7±7.6 | 32.1±6.5 | 0.382 |
| Dinner, % kcal | 31.8±5.3 | 33.7±6.7 | 33.0±9.0 | 0.642 |
| Snack, % kcal | 10.7±8.2 | 12.5±9.3 | 10.8±7.8 | 0.846 |
| Carbohydrate, g | 302.2±52.4 | 333.4±70.0 | 337.1±83.8 | 0.471 |
| Protein, g | 112.1±21.3 | 112.4±34.1 | 110.1±44.0 | 0.527 |
| Fat, g | 79.0±9.7 | 87.2±25.8 | 78.8±41.2 | 0.178 |
| Carbohydrate, % kcal | 51.9±5.0 | 53.8±8.9 | 57.4±12.2 | 0.437 |
| Protein, % kcal | 18.5±2.6 | 17.6±3.9 | 18.5±3.1 | 0.757 |
| Fat, % kcal | 28.8±4.2 | 30.6±7.8 | 28.6±7.3 | 0.737 |
| Day-to-day fluctuations in energy and nutrient intake, 5-day CV, % | ||||
| Total daily energy | 27.0±11.5 | 17.9±7.4 | 29.5±20.8 | 0.191 |
| Carbohydrate | 21.9±9.0 | 19.2±9.1 | 41.0±32.1 | 0.123 |
| Protein | 36.3±15.3 | 32.6±12.4 | 37.4±29.5 | 0.849 |
| Fat | 46.5±17.4 | 37.4±24.4 | 51.5±35.4 | 0.310 |
| Day-to-day fluctuations in energy and nutrient intake, 5-day SD, kcal | ||||
| Total daily energy | 632.2±212.0 | 436.3±171.5 | 605.1±239.4 | 0.052 |
| Carbohydrate | 260.2±94.1 | 250.2±126.1 | 502.1±363.4 | 0.024 |
| Protein | 159.9±65.9 | 138.0±47.5 | 154.4±104.0 | 0.733 |
| Fat | 323.3±104.6 | 285.8±221.1 | 374.1±338.4 | 0.181 |
| Variable | Breakfast, % kcal | Lunch, % kcal | Dinner, % kcal | Mean energy intake per meal |
|---|---|---|---|---|
| Total daily energy (CV), % | –0.17 | 0.49 |
–0.10 | –0.47 |
| Carbohydrate (CV), % | –0.21 | 0.21 | –0.24 | –0.62 |
| Protein (CV), % | 0.18 | 0.18 | –0.24 | –0.32 |
| Fat (CV), % | 0.21 | 0.31 | –0.32 | –0.42 |
| Total daily energy (SD), kcal | –0.36 |
0.52 |
–0.18 | –0.17 |
| Carbohydrate (SD), kcal | –0.16 | 0.06 | –0.32 | –0.43 |
| Protein (SD), kcal | 0.15 | 0.15 | –0.21 | 0.11 |
| Fat (SD), kcal | 0.04 | 0.39 |
–0.27 | –0.04 |
Values are expressed as mean±standard deviation or number (%). T1DM, type 1 diabetes mellitus; DM, diabetes mellitus; BMI, body mass index; SBP, systolic blood pressure; DBP, diastolic blood pressure; FPG, fasting plasma glucose; PP2, 2-hour postprandial glucose; HbA1c, hemoglobin A1c; eGFR, estimated glomerular filtration rate; MDRD, Modification of Diet in Renal Disease; AST, aspartate transferase; ALT, alkaline transferase; TG, triglyceride; HDL, high density lipoprotein; LDL, low density lipoprotein.
Values are expressed as mean±standard deviation or number (%). CV, coefficient of variation; SD, standard deviation; TAR, time above range; TIR, time in range; TBR, time below range.
Values are expressed as mean±standard deviation. CV, coefficient of variation; SD, standard deviation.
Data are presented by Spearman’s partial correlation coefficients after controlling for insulin use. Meal-to-meal fluctuations were defined as intra-personal CV (%) and SD (kcal) between meals. CV, coefficient of variation; SD, standard deviation.