Table 1.
Summarized results of studies meeting literature search and review criteria.
| References | Study population | Sample Size | Groups | Intervention | Time | Outcomes | Results | Assessment of outcome after intervention | Comparison |
|---|---|---|---|---|---|---|---|---|---|
| Sbroma et al. (20) | Diagnosed with T2D, mean HbA1c of 7.5%, average age of 59 | 222 | Intervention (exercise physiologist, endocrinologist, sports medicine physician, psychologist, RDN, educator, nurse) | All participants engaged in a lifestyle intervention after medical examination and interview from psychologist. Intervention included periodic individualized nutrition visits and four RDN-led nutrition education sessions. Anthropometric measurements were compared at baseline, throughout, and post-intervention. | 3 months | HbA1c, waist circumference, BMI, blood pressure | HbA1c changed by a mean value of −0.6 ± 1.1, waist circumference by −3.2 ± 4.7, and BMI by −0.9 ± 2.50. Statistically significant reduction in systolic and diastolic blood pressure. | 24 months follow up, maintained improvements in BMI, weight, waist circumference, blood glucose, HbA1c, blood pressure. | Within group |
| Gilcharan et al. (21) | Diagnosed with T2D and overweight or obese BMI | 320 | Intervention (RDN) vs. usual care | Intervention (tDNA) group received meal counseling, exercise plan, and either counseling with motivational interviewing or conventional counseling. Usual care received dietary and exercise advice. | 6 months | Eating self-efficacy measured through Weight Efficacy Lifestyle Questionnaire (WEL) | WEL scores for the usual care group was 121.9 ± 1.6 at baseline, with a −13.2 ± 2.1 difference at 12 months. The intervention group who received conventional counseling had a baseline WEL score of 134.7 ± 2.6, with an 11.6 ± 2.6 change at 12 months. The intervention group who received motivational interviewing counseling had a baseline WEL score of 129.1 ± 2.3, and a change of 28.9 ± 3.1 at 12 months. | 12 months follow up, sustained WEL scores. | Intervention vs. usual care |
| Johansen et al. (22) | Diagnosed with T2D within the past 10 years, BMI 25–40, not using insulin | 98 | Intervention (RDN, endocrinologist for medication regulation, nurse) vs. usual care (nurse and endocrinologist) | Intervention group received counseling every 3 months, 30–60 min exercise sessions 5–6 times a week, dietary counseling, and a pedometer to monitor steps taken (recommendation to reach at least 10,000 steps/day). Usual care group received T2D information, lifestyle advice, and medical counseling every 3 months from nurse. | 12 months | HbA1c, changes in blood glucose lowering medication, BMI | HbA1C reduced in the intervention group from 6.65 to 6.34%, 6.74 to 6.66% in the standard care group. 73.5% of individuals in the intervention group were able to lower their dosages of glucose lowering medication, compared to 26.4% in the usual care group. −2.01 change in BMI among intervention group, −0.69 usual care group (p = 0.001). | N/A | Intervention vs. usual care |
| Delahanty et al. (23) | Diagnosed with T2D, HbA1C between 6.5 and 11.5 and BMI > 25 kg/m2 (>23 kg/m2 if the participant was Asian) | 208 | Intervention (RDN) | All participants received dietary counseling either from an RDN in a conference call, in person with others, or referral to individual HBI. | 12 months | Cost of each intervention | Individual HBI was the most cost effective ($591) followed by in person counseling ($1,380) and conference call ($1,814). | N/A | Intervention groups |
| Mottalib et al. (25) | Diagnosed with T2D and overweight or obese BMI. Ages 60 ± 10, not using insulin but other T2D medication ≥ 3 months | 108 | Intervention A vs. B vs. C (RDN) | Group A received individualized dietary counseling from RDN regarding eating plan, group B received individualized dietary counseling from RDN regarding meal planning, group C received the same intervention as B but over the phone. | 16 weeks | HbA1c, BMI, waist circumference | No reduction in HbA1c for group A, but a reduction for group B (−0.66) and C (−0.61). BMI decreased for groups A, B, C by −0.43, −1.26, −1.06, respectively. Waist circumference (cm) decreased most in group B (−5.0 cm) and least in group A (−0.4 cm). | N/A | Intervention groups |
| Alonso-Dominguéz et al. (27) | 25–70 years old with T2D | 204 | Intervention (nurse, smartphone app developed with help of RDN and physical activity experts) vs. usual care | Intervention group and usual care received dietary counseling. Intervention engaged in food workshop, exercise, and received smartphone application to assist in adherence to the Mediterranean diet. | 3 months | Post-prandial glucose, blood pressure, waist circumference, BMI, adherence to Mediterranean diet through Mediterranean Diet Adherence Screener (MEDAS) questionnaire | Statistically insignificant reduction in post-prandial glucose, blood pressure, waist circumference, and BMI in the intervention group at 12 months follow up. At 12 months the intervention group received a 8.4 on the MEDAS, usual care received 7.1. | 12 months follow up, sustained adherence to Mediterranean Diet. | Intervention vs. usual care |
| Agee et al. (28) | Diagnosed with T2D >6 months | 224 | Intervention (RDN, PCP) vs. usual care. | Intervention group received HBI from an RDN in addition to their PCP, usual care received care from their PCP. | 12 months | HbA1c, systolic and diastolic blood pressure | The intervention group experienced a mean change of −0.8% HbA1c, a −8.2 mmHg in systolic blood pressure, and −4.3 mmHg in diastolic blood pressure, both statistically significant. | N/A | Intervention vs. usual care |
| Finn et al. (12) | Recent T2D diagnosis, >40 years of age, 2+ cardiovascular risk factors | 164 | Intervention (RDN, nurse, physical activity specialist, physician) | All participants were placed into the intervention group, all engaged in a community-based intervention program with a multidisciplinary team that lead group exercise, individual counseling, and health related seminars. | 16 weeks | HbA1c targets, BMI, systolic and diastolic blood pressure, LDL, perceived quality of life (measured through EQ-VAS score) | BMI decreased by a mean value of 1.1 kg/m2, HbA1c targets were met by 75% of participants compared to 53% at baseline. Systolic blood pressure was reduced by an average of 8.8 mmHg, diastolic by 5.2 mmHg. Perceived quality of life increased by a value of 8. Statistically significant reduction in total and LDL at end of intervention and 1 year. | 12 months follow up, all results maintained, physical activity targets met. | Within group |
| Miller and Akohoue (30) | African American women over 50 years of age with T2D | 12 | Intervention (previously with RDN) | Compared baseline to post-intervention results. Participants filled out dietary self-care questionnaire and were interviewed. | N/A, 2 year follow up results | HbA1c, systolic blood pressure, frequency of high-fat food consumption, spacing out carbohydrates throughout the day, BMI | Reduced HbA1C, reduced systolic blood pressure, reduced frequency in fatty-food consumption, and increased spacing of carbohydrates throughout the day. A statistically significant reduction in frequency of fruit and vegetable intake was observed. Internal factors such as motivation and external factors such as social support were the most prevalent facilitators and barriers. Baseline BMI 40.85, 2 year follow up 41.1. | 24 months follow up, reduction in fruit and vegetable intake and increase in BMI. Maintained reduced HbA1c and systolic blood pressure. Reduced frequency of high fat food consumption, increasing in spacing carbohydrates throughout day. | Within group |
| Saleh et al. (33) | Newly diagnosed with T2D and >25 years of age | 500 | Intervention (RDN) | All participants received 1 h T2D education session from RDN upon enrollment and engaged in group discussions regarding T2D management. | 18 months | T2D knowledge, self-care behaviors, and attitudes measured through a 4 part interviewer administered questionnaire | Total knowledge score pre intervention among male participants was 5.26 ± 2.73 and 5.62 ± 3.03 among female participants. Post-intervention total knowledge score was 9.12 ± 2.31 for male participants, 8.04 ± 2.69 for females. Total attitude scores pre intervention were 80.30 ± 6.61 for males, 79.63 ± 6.47 for females. Post-intervention total attitude scores changed to 85.98 ± 5.86 for males and 85.57 ± 6.25 for females. Pre intervention 8.3, 69.2, 25.8, and 86.7% of participants monitored blood glucose, exercise, engaged in foot care and stopped smoking, respectively, post-intervention 67.7, 85.2, 82.8, and 92.1%, respectively. | N/A | Within group |
| Miklavcic et al. (34) | Older adults with T2D and 2+ chronic conditions | 132 | Intervention (RDN, RN, program coordinator) vs. usual care | Intervention group experienced three in-home visits, participated in monthly group wellness program, monthly case conferencing, and care coordination. | 6 months | Self-efficacy, self-management, and cost of healthcare | No significant differences across groups over 6-month period starting from baseline in self-efficacy, self-management, or cost of healthcare. | N/A | Intervention vs. usual care |
| Markle-Reid et al. (35) | Community-dwelling individuals 65 and older diagnosed with T2D and 2+ comorbidities | 159 | Intervention (RN, RDN, program coordinators, peer volunteer) vs. usual care | Intervention group received up to 3 in home visits from RDN and/or RN, group wellness sessions, care coordination from nurses, peer volunteers, and community partners. Usual care received support from DEC/PCN. | 6 months | Self-management (SDSCA), cost, self-efficacy (self-efficacy for managing chronic disease scale) | Improvement in self-management among intervention group. At 6 months self-efficacy 8.27 ± 1.57 for intervention group, 8.05 ± 1.45 for usual care (P = 0.17), intervention cost neutral. | N/A | Intervention vs. usual care |