Table 2 Overview of clinical studies showing differentially expressed circulating miRs in diabetic patients

1

T2DM

822 individuals from Bruneck study

Plasma

Downregulation of miR-20b, -21, -24, -15a, -126, -191, -197, -223, -320, -486; Upregulation of miR-28-3p

MiR microarray profiling; qPCR

First study to identify differential miR signature in T2DM patients.

[31]

Plasma levels of some miRs changed before the manifestation of diabetes, suggesting miRs as early predictive tool in diabetes and vascular disease

2

T2DM

56 subjects: 18 cases of newly diagnosed T2DM patients (n-T2DM); 19 cases of pre-diabetics and 19 cases of T2DM-susceptible individuals with normal glucose tolerance (s-NGT)

Serum

Upregulation of miR-9, -29a, -30d, -34a, -124a, -146a and −375 in n-T2DM.

qPCR

Significant change in expression of diabetes-related miRs in n-T2DM whiles no dramatic change in pre-diabetics and s-NGT.

[163]

miR-34a most significantly changed in all the 3 study groups.

3

T2DM and obese

13 patients with T2DM; 16 obese patients (OB) with T2DM; 20 obese patients (OB-T2DM) and 20 healthy volunteers.

Serum

miR-15b, -138, -376a and −503

Pre-screening with pre-aliquoted miR PCR panels and validation of selected miRs by qPCR

First study to identify differential miR signature in T2DM patients, OB, OB-T2DM and healthy subjects.

[164]

Biomarker potential of miR-15b, miR-138 and miR-376a to differentiate OB from OB-T2DM and T2DM.

Biomarker potential of miR-138 and miR-503 to differentiate T2DM from OB-T2DM.

4

T2DM, Individuals with or without metabolic syndrome

265 individuals: n = 50 with metabolic syndrome; n = 50 with T2DM; n = 89 with hypercholesterolemia; n = 30 with hypertension and n = 46 healthy controls

Blood

miR-23a, -27a, -103, --132, -150, -192, -195, -197, -320a, -375, and −509-5p

MiR microarray profiling; qPCR of selected miRs

Correlation between aberrant miR expression and risk factors in diabetes and its vascular complications.

[165]

5

T2DM with or without vascular complications

36 individuals: 12 T2DM patients without any chronic complications; 12 T2DM patients with macrovascular and 12 T2DM patients with microvascular complications.

Serum

52 miRs in T2DM with macrovascular and 68 miRs in T2DM with microvascular complications

MiR microarray profiling; qPCR of selected miRs

Upregulation of miR-31a in T2Dm with microvascular complications

[166]

6

T1DM

Hvidoere (275 T1DM patients), Danish (129 T1DM patients) and Copenhagen Puberty (151 T1DM patients) Cohorts

Serum

Upregulation of miR-24, -25, 26a, -27a/b, -29a, -30a-5p, -148a, -152, -181, -200a and −210

MiR microarray profiling; qPCR

miR-25 negatively associated with beta-cell function and positively associated with glycaemic control

[167]