Type 2 diabetes: lifestyle change vs. standard medical care

Aim

Type 2 diabetes (T2D) is a growing global issue affecting 10.5% of the worldwide adult population. 

A poor diet is the most significant risk factor, second only to a high body mass index.

The purpose of this study was to determine whether an intensive lifestyle intervention that combines a whole-food, plant-based diet (WFPB) with moderate exercise would improve glycaemic control, cardiovascular health, and the need for glucose-lowering medication more effectively than standard medical care (SMC). 

Method

The clinical trial was 24 week parallel-arm, randomised control, including participants aged 18-75 years in the Republic of the Marshall Islands which has the seventh-highest prevalence of diabetes worldwide.

Participants were representative of Marshallese adults with T2D. A HbA1c of ≥64 mmol/mol (≥8.0%) or a diagnosis of T2D and use of glucose-lowering medication were criteria for inclusion.

The intervention group was instructed to eat a culturally tailored WFPB diet consisting of 75–100% of energy from whole, unprocessed plant foods, such as vegetables, legumes, whole grains and fruit and to do moderate intensity aerobic exercise and resistance training for a minimum of 30–60 minutes per day for 24 weeks.

During weeks 1–12, participants received prepared meals, attended group exercise sessions and received group instruction on eating healthfully, cooking, exercising and managing stress. The intensity of support progressively decreased until participants were told to carry out the intervention independently between weeks 13–24.

The control group was treated using glucose-lowering pharmacotherapy according to SMC and instructed to maintain their current diet and physical activity levels.

Outcomes were assessed at 0, 2, 6, 12 and 24 weeks. Primary outcome were glycaemic control, measured by HbA1c, fasting glucose, fasting insulin, HOMA-IR and diabetes medication use. Secondary outcomes were cardiovascular risk factors, including body weight, waist circumference, lipids, systolic blood pressure (SBP), diastolic blood pressure (DBP), resting heart rate, high-sensitivity C-reactive protein (hsCRP) and cardiovascular medication use.

Key findings

169 participants were randomised (SMC: n=90; PB+Ex: n=79), 31 withdrew prior to baseline data collection. 72 participants received SMC, with 66 receiving the diet and exercise (PB+Ex) intervention.

Participants had a mean age (±SD) of 54 ± 9 years, a BMI of 29.8 ± 4.9 kg/m2, an HbA1c of 90 ± 23 mmol/mol (10.4 ± 2.1%) and a fasting glucose of 12.9 ± 4.2 mmol/l, indicating high rates of uncontrolled type 2 diabetes.

Fig. 1 shows the diet plus exercise intervention was more effective than SMC at improving HbA1c (a) and medication effect score (MES) + HbA1c (b) if glucose-lowering medication doses had not been changed. The intervention also improved (c) fasting glucose at all timepoints except week 24 and (d) fasting insulin at week 2 only. Data shown are least-squares means ± SEMs. *p<0.05

Fig. 2 shows changes in participant T2D remission and medication use. (a) the intervention was more effective than SMC at inducing T2D remission. (b) About one-quarter of participants with a baseline HbA1c <75 mmol/mol (<9%) achieved remission. The PB+Ex group also significantly reduced their doses of (c) diabetes medications and (d) cardiovascular medications. Data shown are proportions (%). *p<0.05

Fig 3. shows The PB+Ex intervention was more effective than SMC at lowering (a) body weight and (h) hsCRP. The intervention also improved (b) total cholesterol, (c) triglycerides, (e) SBP, (f) DBP and (g) heart rate at intermediate timepoints but not at week 24. There were no differences in (d) LDL-cholesterol. Data shown are least-squares means ± SEMs. *p<0.05

There were no adverse events related to the protocol.

Conclusion

An intervention of a WFPB diet plus 30-60 minutes of exercise per day is superior to SMC for improving HbA1c, inflammation, weight and waist circumference while reducing the need for diabetes and cardiovascular medications. The intervention also induces T2D remission in some patients.

Following a WFPB diet and taking regular exercise is more effective at improving glycaemic control than SMC centred around medication management.

During the 24-weeks of this study the SMC group increased their dose of glucose lowering medications by the equivalent of 360 mg/day of metformin, whereas the diet and exercise group reduced their dose by 820 mg/day (a between-group difference of 1180 mg/ day).

The intervention decreased fasting glucose by a dramatic 4.0 mmol/l relative to baseline within only 2 weeks. Suggesting improvements were due to changes in diet quality and/or physical activity rather than weight loss.

The authors conclude that a WFPB diet with moderate exercise can be offered as a highly effective, evidence-based lifestyle intervention for individuals with type 2 diabetes.

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