Table 1.
| Publication | Ethnic and duration of T2DM | Material/criteria | Number of T2DM patients/control | Characteristics of the T2DM patients | Alteration of BDNF level with T2DM | Positive-correlated parameters with BDNF level | Negative-correlated parameters with BDNF level | Independent association with BNDF level |
|---|---|---|---|---|---|---|---|---|
| Suwa et al. [9] 2006 | Japanese female, newly diagnosed | (i) Serum (ii) No treatment |
24/7 | (i) BMI (kg/m2): 26.1 ± 3.3 (ii) HbA1c (%): 6.52 ± 0.90 (iii) HOMA-IR: 2.32 ± 1.38 |
↑ Increased | (i) BMI (ii) Body fat percent (iii) Subcutaneous fat (iv) HOMA-IR (v) Triglycerides (vi) Fasting glucose (vii) HbA1c (weak correlation) |
(i) Age | |
|
| ||||||||
| Krabbe et al. [53] 2007 | Caucasian, long standing | (i) Plasma (ii) No treatment with insulin (iii) No antidiabetic drug for 1 week before the blood sampling (iv) No drug 24 hours before the blood sampling |
Diabetes obese/obese: 46/41 Diabetes nonobese/nonobese: 50/62 |
Diabetes obese patients: (i) BMI (kg/m2): 35.5 ± 0.7 (ii) Fasting glucose (mmol/L): 9.6 ± 0.9 Diabetes nonobese patients: (iii) BMI (kg/m2): 26.6 ± 0.3 (iv) Fasting glucose (mmol/L): 9.9 ± 0.6 |
↓ Decreased with patient with diabetes compared to nondiabetic ↓ Decreased with obese patients compared to nonobese |
(i) CRP | (i) Fasting glucose level (strong correlation) | (i) Obesity |
|
| ||||||||
| Fujinami et al. [58] 2008 | Japanese, long standing | (i) Serum (ii) No treatment with insulin (iii) No treatment with thiazolidinedione (iv) No hormonal treatment |
112/80 | (i) BMI (kg/m2): 23.1 ± 3.1 (ii) Fasting glucose (mmol/L): 8.51 ± 2.18 (iii) HbA1c (%): 7.4 ± 1.3 (iv) HOMA-R: 2.42 ± 2.16 |
↓ Decreased ↑ Increased female patients with diabetes compared to male patients with diabetes |
(i) Immunoreactive insulin (ii) HOMA-R |
(i) Adiponectin level (weak correlation) | |
|
| ||||||||
| Zhen et al. [56] 2013 | Han Chinese, long standing | (i) Serum (ii) No treatment with insulin (iii) Some patients received metformin and/or repaglinide |
208/212 | (i) BMI (kg/m2): 25.9 ± 3.8 (ii) Fasting glucose (mmol/L): 9.2 ± 3.1 (iii) HbA1c (%): 7.5 ± 2.0 |
↓ Decreased | (i) Delayed memory index (ii) Cognitive deficit |
(i) Fasting glucose level (ii) Duration of illness |
|
|
| ||||||||
| He et al. 2014 [55] (pilot study) | Chinese, long standing | (i) Serum (ii) No data |
37/37 | (i) BMI (kg/m2): 26.4 ± 2.3 (ii) Fasting glucose (mmol/L): 8.37 ± 3.39 (iii) HbA1c (%): 9.11 ± 2.92 |
↓ Decreased ↑ Increased female patients with diabetes compared to male patients with diabetes |
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|
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| Passaro et al. [57] 2014 | Caucasian, long standing | (i) Plasma (ii) Some patients received antidiabetic drug (iii) Antihypertension drug |
37/154 | ↓ Decreased | (i) Total cholesterol (ii) LDL |
(i) Age (ii) Systolic blood pressure |
(i) T2DM | |
|
| ||||||||
| Boyuk et al. [52] 2014 | Caucasian, long standing | (i) Serum (ii) Some patients received oral antidiabetic drug (iii) Oral antidiabetic drug plus insulin (iv) Insulin (v) Antihypertension drug (vi) Antilipid drug |
88/33 | (i) BMI (kg/m2): 31.52 ± 5.80 (ii) Fasting glucose (mg/dL): 170.36 ± 91.21 (iii) HbA1c (%): 8.30 ± 2.37 (iv) HOMA-IR: 3.73 ± 3.05 |
↑ Increased | (i) HOMA-IR (ii) Triglyceride (iii) WBC |
(i) T2DM | |
|
| ||||||||
| Li et al. [54] 2015 | Chinese, long standing | (i) Serum (ii) Some patients received insulin (iii) Lipid-lowering medication (iv) Blood pressure treatment |
292/200 | (i) BMI (kg/m2): 26.8 (24.7–29.4) (ii) Fasting glucose (mmol/L): 8.6 (6.7–9.9) (iii) HbA1c (%): 7.9 (6.4–9.2) (iv) HOMA-IR: 3.80 (2.35–5.47) |
↓ Decreased | (i) Fasting glucose level (ii) Duration of illness (iii) BMI (iv) CRP |
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BMI: body mass index; HbA1c: glycated hemoglobin; HOMA-IR: homeostatic model assessment insulin resistance; CRP: c-reactive protein; LDL: low-density lipoprotein.