Nurse-Led Motivational Interviewing for Improving Health Outcomes in Type 2 Diabetes

Introduction

Type 2 diabetes mellitus is a chronic condition whose effective management depends substantially on patients’ sustained engagement in health behaviors, including dietary modification, regular physical activity, and consistent medication adherence, over an extended and often lifelong disease course. Despite widespread availability of effective pharmacologic therapy and structured diabetes education, a substantial proportion of patients with type 2 diabetes do not achieve recommended glycemic targets, a gap frequently attributed not to insufficient clinical knowledge, but to the practical difficulty of initiating and sustaining behavior change in the context of competing life demands, ambivalence, and variable readiness to change (Funnell et al., 2020).

Motivational interviewing is a patient-centered, collaborative counseling approach originally developed within the addiction treatment field and subsequently adapted for chronic disease management, grounded in the principle that sustainable behavior change is most effectively elicited by helping patients articulate and strengthen their own internal motivation for change, rather than through direct persuasion or didactic instruction from the clinician (Miller & Rollnick, 2018). Motivational interviewing has demonstrated benefit across a range of chronic disease contexts, including substance use, weight management, and cardiovascular risk reduction, and has been increasingly incorporated into diabetes care as a complement to standard structured diabetes education.

While motivational interviewing has been examined within diabetes populations previously, much of the existing evidence base encompasses interventions delivered by a heterogeneous mix of clinician types, including physicians, health coaches, psychologists, and nurses, often without clear isolation of the nurse-delivered format as a distinct intervention condition (Ekong & Kavookjian, 2019). This lack of delivery-model specificity limits the ability of health systems considering nurse-led motivational interviewing program investment to draw directly applicable conclusions from the existing literature, particularly given that nurses represent a comparatively scalable and accessible workforce for delivering structured counseling interventions relative to specialized behavioral health personnel.

Given the persistent gap between available diabetes pharmacotherapy and achieved glycemic control, and the need for delivery-model-specific evidence regarding nurse-led motivational interviewing, this study aimed to evaluate the effect of a structured, nurse-led motivational interviewing intervention on glycemic control and related secondary health outcomes among adults with type 2 diabetes, in comparison to standard diabetes care delivered through routine physician-directed counseling.

Methods

This study employed a randomized controlled trial design conducted at four outpatient primary care clinics affiliated with a single regional health system, over an 8-month enrollment and follow-up period. Adults aged 18 years or older with a diagnosis of type 2 diabetes and a baseline HbA1c of 7.5% or greater were eligible for inclusion. Patients with type 1 diabetes, active pregnancy, or a life expectancy of less than 12 months were excluded. Eligible patients were randomized in a 1:1 ratio to either the nurse-led motivational interviewing arm or the standard care arm using a computer-generated randomization sequence stratified by clinic site. A total of 228 patients were randomized: 114 to the motivational interviewing arm and 114 to standard care.

Patients randomized to the motivational interviewing arm participated in six individual counseling sessions delivered over 6 months by registered nurses who had completed a standardized 16-hour motivational interviewing training program and demonstrated competency through recorded session review using the Motivational Interviewing Treatment Integrity (MITI) coding system. Sessions employed core motivational interviewing techniques, including open-ended questioning, affirmation, reflective listening, and summarizing, to elicit patients’ own reasons for and ambivalence toward behavior change, with each session incorporating collaborative goal-setting and review of progress toward previously established, patient-identified goals. Patients randomized to standard care continued to receive diabetes management exclusively through routine physician office visits, which included standard counseling on diet, activity, and medication but did not include structured, dedicated motivational interviewing sessions.

Data were collected at baseline, 3 months, and 6 months for both study arms, encompassing three primary measurement domains:

1.Clinical measures, including HbA1c obtained through standard laboratory venipuncture, systolic and diastolic blood pressure measured using a standardized automated office protocol, and body mass index calculated from measured height and weight.

2.Diabetes self-efficacy, assessed using the Diabetes Empowerment Scale, a validated instrument measuring patients’ perceived capability to manage the psychosocial and behavioral demands of diabetes self-management.

3.Health behavior measures, including self-reported dietary adherence and physical activity level, assessed using validated brief self-report instruments at each measurement time point.

The primary outcome was change in HbA1c from baseline to 6 months. Secondary outcomes included change in systolic blood pressure, body mass index, and diabetes self-efficacy score. Analysis was conducted on an intention-to-treat basis using analysis of covariance (ANCOVA), adjusting for baseline value of the respective outcome, age, and diabetes duration. Statistical significance was set at p < .05, and analyses were conducted using SPSS version 29.

Results

Baseline characteristics did not differ significantly between the motivational interviewing arm and the standard care arm across any measured demographic or clinical variable, supporting adequacy of randomization (Table 1). A total of 213 patients (93.4%) completed the 6-month follow-up assessment, with completion rates not differing significantly between study arms.

At 6 months, mean HbA1c had decreased by 1.1 percentage points in the motivational interviewing arm, compared to a decrease of 0.4 percentage points in the standard care arm. In the adjusted ANCOVA model, the motivational interviewing intervention was associated with a significantly greater reduction in HbA1c relative to standard care (adjusted mean difference = −0.7%, 95% CI −1.0 to −0.4, p < .001), after adjusting for baseline HbA1c, age, and diabetes duration.

Secondary outcomes were consistently more favorable in the motivational interviewing arm across all measured domains (Table 2). Systolic blood pressure decreased by a mean of 7.8 mmHg in the motivational interviewing arm compared to 2.9 mmHg in the standard care arm, and body mass index decreased by a mean of 0.9 kg/m² compared to 0.2 kg/m² in the standard care arm, both representing statistically significant between-group differences after adjustment. Diabetes self-efficacy scores, measured using the Diabetes Empowerment Scale, improved substantially more in the motivational interviewing arm, with an adjusted between-group difference of 9.0 points. The proportion of patients achieving the clinical target of HbA1c below 7.0% at 6 months was significantly greater in the motivational interviewing arm than in the standard care arm, at 39.3% versus 20.8% respectively. As illustrated in Figure 1, the between-group divergence in HbA1c trajectory was already evident at the 3-month assessment and continued to widen through the 6-month endpoint, suggesting a cumulative rather than solely front-loaded intervention effect. Subgroup analysis indicated that the magnitude of HbA1c improvement in the motivational interviewing arm was numerically greatest among patients with the highest baseline HbA1c values, consistent with a pattern observed in related structured diabetes intervention research.

Discussion

The findings of this randomized controlled trial demonstrate that a structured, nurse-led motivational interviewing intervention produced clinically meaningful improvement across glycemic control, blood pressure, body mass index, and diabetes self-efficacy relative to standard diabetes care, with the magnitude of glycemic benefit, an adjusted between-group HbA1c difference of 0.7 percentage points, consistent with reductions reported in prior motivational interviewing research spanning heterogeneous clinician delivery models (Ekong & Kavookjian, 2019), while providing delivery-model-specific evidence supporting the nurse-led format in particular.

The consistent improvement observed across multiple, mechanistically distinct outcome domains, spanning glycemic control, blood pressure, weight, and self-efficacy, suggests that the motivational interviewing intervention’s benefit was not confined to a single, narrowly targeted behavior, but reflected a broader improvement in patients’ overall engagement with diabetes self-management. This pattern is consistent with the theoretical basis of motivational interviewing, which does not target a single specific behavior in isolation but instead seeks to strengthen patients’ general motivation and perceived capability for health-related behavior change, an effect that would plausibly generalize across the multiple interrelated behavioral domains relevant to diabetes management, including diet, activity, and medication engagement (Miller & Rollnick, 2018).

The progressive widening of the between-group HbA1c difference from 3 to 6 months, illustrated in Figure 1, suggests that the intervention’s benefit accumulated over the course of the 6-month program rather than being driven primarily by an early, front-loaded counseling effect. This pattern aligns with the structured, longitudinal design of the intervention, which incorporated collaborative goal-setting and progress review across six sequential sessions, and suggests that sustained, longitudinal counseling contact, rather than a single initial counseling encounter, may be important for achieving the full magnitude of benefit associated with motivational interviewing in this population.

This study has several limitations. The open-label nature of the trial, given the impracticality of blinding participants or delivering nurses to group assignment, introduces the possibility that differential attention or expectation effects contributed to the observed between-group differences. The four-site setting, while providing some diversity in clinic context, remains limited to a single regional health system, and further research across more diverse healthcare settings would strengthen generalizability. The 6-month follow-up period does not establish whether the observed benefits are sustained following completion of the structured counseling program, and future research incorporating extended follow-up beyond the active intervention period would help characterize the durability of this effect. Despite these limitations, the consistency and clinical coherence of the findings across multiple outcome domains support the integration of structured, nurse-led motivational interviewing into routine outpatient care for adults with type 2 diabetes, particularly as a complement to existing structured diabetes education and pharmacologic management.

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