Table 1 Characteristics summary of all included reviews

Systematic Review and Meta-Analysis

 Anderson A (2022) [47]

Type 2

10

Significant reduction in HbA1c MD − 0.465% (95% CI: − 0.648% to − 0.282%)

n = 9

N/A

1 study conducted education sessions by interactive videoconferencing, which was effective in improving HbA1c

 Correia J C (2021) [43]

Type 1, type 2 and gestational

31

Significant reduction of HbA1c MD −0.38% (95% CI: −0.52% to −0.23%)

n = 28

Significant effect on fasting blood sugar, adherence to treatment, knowledge of diabetes and self-efficacy. No significant effect on BMI, total cholesterol, and triglycerides

4 studies identified videoconferencing as part of web-based systems, with mean difference of −0.89% (95% CI: −0.85 to 0.08)

 De Groot J (2021) [44]

Type 2

43

Significant reduction in HbA1c MD −0.486% [95% CI −0.561% to −0.410%) n = 43

Significant reductions in blood pressure, blood glucose, weight. Improved mental and physical QoL

4 studies used interactive videoconference with mean reduction in HbA1c of 0.845% (95% CI −1.144 to −0.546, P < 0.001)

 Eberle C (2021)^[ [32]

Type 2

99

Significant reduction of HbA1c MD −1.15% (95% CI: − 1.84% to –0.45%)

n = 2

Combination of real-time and asynchronous interventions most effective in improving fasting blood glucose, blood pressure, body weight, BMI, and quality of life

12 studies analysed videoconferencing and video consulting. 8 studies reported clear reduction in HbA1c values. Weekly video conferences showed significant decline is HbA1c and lower fasting blood glucose. No change in BMI, blood pressure and quality of life. In person visits showed significant weight loss

 Faruque L (2017) [31]

Either type 1 or type 2 or both

111

Significant reduction of HbA1c MD—0.28%; 95% CI −0.37% to −0.20%)

n = 87

No evidence of effect on QoL or mortality and reduced risk of hypoglycaemia

5 studies reported healthcare providers initiated communication using videoconferencing and 1 study involved video messaging. Videoconferencing with health care providers mainly included nurses and/or physicians. People with diabetes initiated communications did not involve any video components

 Hangaard S (2021) [45]

Type 2

246

Significant reduction in HbA1c MD −0.415% [95% CI −0.482% to −0.348%)

n = 168

No significant effect on BMI

Not included in search strategy and not reported in results

 Hu Y (2019) [30]

Either type 1 or type 2 or both

14

Significant reduction of HbA1c MD −0.28% (95% CI: −0.45% to −0.12%) n = 13

No significant effect on BMI. MD −0.27; (95% CI:−0.86% to −0.31%); n = 7

Videoconferencing and video recording were part of search terms. Findings not reported

 Huang Z (2015) [33]

Type 2

18

Significant reduction of HbA1c MD −0.54% (95% CI: −0.75% to −0.34%) n = 18

No significant differences in BMI, body weight, and hypoglycaemic events

Not reported as part of the interventions or results

 Lee S W H (2017) [20]

Type 2

107

Significant reduction of HbA1c MD −0.43% (95% CI: −0.64% to −0.21%) n = 93

No significant changes in cardiovascular risk factors, risk of hypoglycaemia and quality of life

16 studies with telemonitoring and 11 studies with telementoring interventions, some of which included video conferencing

 Marcolino M S (2013) [37]

Type 1 or type 2

15

Significant reduction of HbA1c MD −0.44% (95% CI: −0.61% to −0.26%) n = 13

Reduction in LDL-cholesterol, no effect on blood pressure and tendency to reduce BMI

1 study used videoconferencing as part of telemedicine strategies

 Michaud T L (2021) [24]

Type 2

17

Significant reduction of HbA1c MD −0.30% (95% CI: −0.31% to −0.29%) n = 15

Weight change (kg)—MD of pre-post difference between telehealth and usual care was −0.62 (95% CI: −0.7 to −0.45)

2 studies had videoconferencing as part of real-time feedback and reported improvement in HbA1c

 Robson N (2021) [48]

Type 2

29

Significant reduction of HbA1c MD −0.18% (95% CI: 0.35% to −0.01%) n = 21

Significant reduction in outpatient, Emergency Department (ED) visits, planned hospitalisations, and LDL cholesterol levels

3 studies used video teleconferencing and 1 study found statistically significant reduction in mean HbA1c levels. Other studies reported reduction in BP. 1 study used video education and reported significant reduction in mean HbA1c and significant improvement in body weight, BMI, waist circumference and fasting blood glucose

 So C F (2018) [42]

Either type 1 or type 2

7

Significant reduction of HbA1c MD—0.64% (95% CI: −1.01% to −0.26%) n = 8

No significant effect on fasting plasma glucose (MD = −0.26%; 95% CI: −1.05% to 0.53%) n = 4

Not reported as part of the search or telehealth interventions

 Su D (2015) [28]

Either type 1 or type 2 or both

92

Significant reduction of HbA1c post intervention varied from −3.2% to 0.70%. Mean ending HbA1c ranged from 6.26% to 9.21%; n = 92

No significant effect of having a nutritional counselling as part of the telemedicine interventions

11 studies used teleconference and 2 studies used educational videos. Nutritional counselling via SMS, telephone or videoconference showed similar effects

 Su D (2016) [29]

Either type 1 or type 2 or both

49

Significant reduction of HbA1c pre and post-tests varied from 2.2% to 0.5% in intervention groups and from 1.3% to 0.6% in control groups; n = 55

Most effective for type 2 diabetes than type 1 and among people with diabetes of ages 40 or older. Interventions of 6 months or less showed greater effect than longer programs

2 studies used videoconferencing and 1 study included video messages. Effect of video conferencing not reported

 Tchero H (2019) [21]

Type 1 and type 2

38

Significant reduction of HbA1c MD −0.37 (95% CI: −0.43% to −0.31%); n = 42

Most effective for type 2 diabetes than type 1 diabetes; among people with diabetes of ages 40 or older than younger population; and longer duration interventions of over 6 months

2 studies included interventions using live videoconferencing for remote consultations. 1 study used video messages. Effect of video conferencing not reported

 Wu C (2018) [35]

Type 1 or type 2

19

Significant reduction of HbA1c MD −0.22% (95% CI: −0.28% to −0.15%) n = 16

Reduction of blood pressure. No change in BMI and quality of life

2 studies delivered education via videoconferencing. Effect of video conferencing not reported

 Zhai Y K (2014) [25]

Type 2

47

Significant reduction of HbA1c MD −0.37 (95% CI: −0.49% to −0.25%); n = 35

2 studies analysed cost-effectiveness and revealed ICERs (Incremental cost-effectiveness ration) of $491 and $29,869 per capita for each unit reduction in HbA1c, for the telephone- and internet-based (includes video conferencing) interventions, respectively

1 study included live videoconferencing as part of IDEATel internet-based trial. Meta-analysis showed HbA1c reduction of 0.29% (95% CI: 0.12% to 0.46%)

Systematic Review

 Cassimatis M (2012) [23]

Either type 1 or type 2 or both

13

Significant improvement in HbA1c

5 out of 8 studies reported significant improvements in dietary adherence and physical activity. 4 out of 9 found significant improvement in blood glucose self-management frequency. 8 studies assessed medication adherence and only 3 reported improvements

1 study found ‘Persistent viewers’, who viewed more than 10 self-care video messages per month experienced a significant reduction in HbA1c of 0.6% over 12 months

 Greenwood D A (2014) [38]

Type 2

15

Significant reduction in HbA1c levels

Not all 7 key elements of structured monitoring recommended by the IDF were included in telehealth remote patient monitoring interventions

3 studies used provider feedback methods by videoconferencing. 1 study used educational nuggets. Effect of videoconferencing was reported as part of the interventions

 Hossain M M (2019) [27]

NCDs including diabetes

13

Significant reduction in HbA1c

Improvement in medication adherence, self-management, and lifestyle modification

1 study provided access to educational videos to the telephonic follow up intervention group. Significant reduction of HbA1c reported

 Jalil S (2015) [39]

Type 2

19

Mixed results on the effectiveness of telemedicine on medical outcomes

Positive effect on behavioural improvements

1 study used video instructions. Effect not reported

 Kaveh M H (2021) [22]

Either type 1 or type 2 or both

18

Biomedical outcomes: positive effect on glycaemic control; diet and exercise monitoring led to reducing BMI; improved cholesterol and blood pressure

Behavioural outcomes showed self-monitoring and self-efficacy; Psychosocial outcomes improved depression and increased social support. Quality of life improved

8 studies used videoconference interventions. Effective in improving behavioural outcomes

 Marsh Z (2021) [26]

Either type 1 or type 2 or both

9

Significant reduction in HbA1c of 0.8%—1.3%

Enhanced diabetes self-management adherence and increased satisfaction of people with diabetes and HCPs

4 studies used videoconferencing. Effective in improving HbA1c and enhances communication between people with diabetes and healthcare professionals

 McDaniel C (2021) [46]

Type 1, type 2, or prediabetes

21

Motivational Interviewing (MI) based telehealth seems most effective for improving A1C, systolic blood pressure, diabetes self-efficacy, and physical activity behaviours

Significant effect on behaviour change, medications, physical activities, and diabetes knowledge

1 study solely used videophone calls for nurse practitioner delivered motivational interviews. Identified as a research gap to evaluate the effect

 McLendon S F (2017) [34]

Both type 1 and type 2

14

Significant reduction of (baseline 8.6 ± 0.3% telemedicine vs. 8.9 ± 0.4 usual care; completion 6.6 ± 0.2 telemedicine vs. 8.1 ± 0.2% usual care, P = 0.02)

Improved patient empowerment, self-care, adherence to diet, glucose monitoring, access to specialist care and preference to use technology

All studies included video consultation. Improved glycaemic control after one video consultation and continued to show progress in lowering HbA1c levels

 Mushcab H (2015) [40]

Type 2

19

Real-time management and remote monitoring of T2DM people with type 2 diabetes resulted in a significant decrease in HbA1c level

mixed results for clinical outcome measures such as HbA1c, BMI, and cholesterol level. High acceptance of technology

Studies involving videoconferencing interventions were excluded

 Sim R (2021) [49]

Type 2

20

Higher patient satisfaction could be achieved by understanding patient preferences and technology support

Support for technology adoption. Increases Access and saves time

2 studies used videoconferencing as part of the interventions- Enablers and barriers identified

 Van Den Berg N (2012) [36]

Cardiovascular and diabetes

68 (18 diabetes)

Improved glycaemic control for people with diabetes with mean age between 60 and 69 years

Clear trend towards better results for behavioural outcomes, such as adherence to medication or diet, physical activity, self-efficacy, and managing the disease compared to medical outcome-categories

19 studies delivered telemedicine case management included videoconferencing. Effective in improving personal contact and better outcomes

 Wickramasinghe S I (2016) [41]

Diabetes

14

N/A

Enablers and barriers to telemedicine identified

1 study used videoconferencing for specialist’s consultations. Effective in increasing number of teleconsultations