Table 2.
Summary of characteristics of participants.
| # | Study | Sample size (T, I, C) | Mean age (years) | Mean BMI (kg/m2) at baseline | Inclusion criteria | Exclusion criteria | Blood glucose concentration for diagnosis of prediabetes | Cut-off for diagnosis of diabetes |
|---|---|---|---|---|---|---|---|---|
| (1) | Knowler et al. [17] | T = 3234 I = 1079 C = 1082 Total of I and C = 2161 |
Overall = 34.0 ± 6.7 I = 50.6 ± 11.3 C = 50.3 ± 10.4 |
Overall = 34.0 ± 6.7 I = 33.9 ± 6.8 C = 34.2 ± 6.7 |
≥25 years old, BMI ≥ 24, IGT | Diabetes, taking glucose altering medication, illness that seriously reduces life expectancy, or ability to participate in the trial | 2 hours after 75 g oral glucose load 7.8 mmol/L to 11.0 mmol/L | ≥11.1 mmol/L 2 hours after 75 g oral glucose load. ≥7.0 mmol/L fasting plasma glucose |
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| (2) | Kosaka et al. [18] | Men only T = 458 I = 102 C = 356 |
Mean age not stated | I = 24.0 ± 2.3 C = 23.8 ± 2.1 |
IFG | Diabetes, malignant neoplasm, suspected or diagnosed disease of liver, pancreas, endocrine organs, or kidneys, ischaemic heart disease, or cerebrovascular disease | 2 hours after 75 g oral glucose load 7.8 mmol/L to 11.0 mmol/L | Fasting plasma glucose of ≥7.8 mmol/L |
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| (3) | Lindström et al. [19] | T = 522 I = 265 C = 257 |
I = 55 ± 7 C = 55 ± 7 |
I = 31.4 ± 4.5 C = 31.1 ± 4.5 |
40–64 years old, BMI ≥ 25, IGT | Diabetes | States based on WHO criteria | Level for diagnosis not stated |
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| (4) | Moore et al. [20] | T = 307 I = 208 C = 99 |
Overall = 62.5 ± 10.1 | I = 29.66 ± 5.33 C = 29.79 ± 4.94 |
IGT | Diabetes | 2 hours after 75 g oral glucose load 7.8 mmol/L to 11.0 mmol/L | >11.0 mmol/L 2 hours after 75 g oral glucose load. ≥7.0 mmol/L fasting plasma glucose |
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| (5) | Penn et al. [21] | T = 102 I = 51 C = 51 |
Overall = 57.2 ± 1.7 | I = 34.1 ± 5.5 C = 33.5 ± 4.6 |
≥40 years old, BMI ≥ 25, IGT | Diabetes, chronic illness that meant being unable to participate in moderate physical activity, special diet for medical reasons | 2 hours after 75 g oral glucose load 7.8 mmol/L to <11.1 mmol/L | ≥11.1 mmol/L 2 hours after 75 g oral glucose load |
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| (6) | Ramachandran et al. [22] | T = 531 I = 133 C = 136 Total of I and C = 269 |
I = 46.1 ± 5.7 C = 45.2 ± 5.7 |
I = 25.7 ± 3.3 C = 26.3 ± 3.7 |
IGT | Diabetes | 2 hours after 75 g oral glucose load 7.8 mmol/L to 11.0 mmol/L | Fasting plasma glucose of ≥ 7.8 mmol/L |
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| (7) | Roumen et al. [23] | T = 147 I = 74 C = 73 |
I = 54.2 ± 5.8 C = 58.4 ± 6.8 |
I = 29.6 ± 3.8 C = 29.2 ± 3.3 |
IGT | Diabetes, chronic illness, medication known to change glucose concentrations | 2 hours after 75 g oral glucose load 7.8 mmol/L to <12.5 mmol/L | States based on WHO (1999) criteria |
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| (8) | Saito et al. [24] | T = 641 I = 311 C = 330 |
Median age only stated at: I = 50 (44–54) C = 48 (41–54) |
I = 26.9 ± 2.6 C = 27.1 ± 2.6 |
30–60 years old, BMI ≥ 24, IFG |
Diabetes, ischaemic heart disease, stroke, chronic nephritis, pituitary disease, thyroid disease, adrenal gland disease, mental illness, gastrectomy, malignant tumour, medication effecting glucose concentrations | Fasting plasma glucose 5.6 mmol/L 6.7 mmol/L | ≥11.1 mmol/L 2 hours after 75 g oral glucose load. ≥7.0 mmol/L fasting plasma glucose |
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| (9) | Xu et al. [25] | T = 88 I = 46 C = 42 |
I = 60.35 ± 9.78 C = 56.55 ± 8.61 |
I = 26.80 ± 3.13 C = 25.72 ± 3.83 |
≥25 years old, BMI ≥ 18.5, IFG | Diabetes, stroke, CHD, malignancies in past 5 years, suspected disease of liver, pancreas, or kidney | 2 hours after 75 g oral glucose load 7.8 mmol/L to 11.0 mmol/L | Diabetes cut-off not stated |
T: total; I: intervention; C: control; IGT: impaired glucose tolerance; IFG: impaired fasting glucose; BMI: body mass index (kg/m2); WHO: World Health Organization.