(DCP080) THE ASSOCIATION BETWEEN THE CLINICAL PORTFOLIO DIET SCORE AND HBA1C IN TYPE 2 DIABETES MELLITUS: AN EXPLORATORY ANALYSIS OF TWO RANDOMIZED DIETARY TRIALS

Background: The Portfolio Diet is rich in low glycemic index (LGI) foods including pulses, soy, oats, barley and temperate climate fruit. Evidence supports LGI dietary patterns for the prevention and management of type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). While strong evidence supports clinically meaningful reductions in cholesterol, evidence on the relationship between the Portfolio Diet and diabetes management is lacking. To explore the relationship between the Portfolio Diet and glycemic control, we assessed the association between the Portfolio Diet and HbA1c in an exploratory analysis of 2 completed randomized trials of LGI versus high-cereal fibre diets in adults with T2DM.

METHODS AND RESULTS: Dietary and HbA1c data were available at baseline and 6-months in 267 participants from either trial (clinicaltrials.gov identifiers: NCT00438698, NCT00438698). Adherence to the Portfolio Diet and its components (plant protein, viscous fibre, nuts, phytosterols, monounsaturated fatty acids) were determined using the clinical Portfolio Diet Score (cPDS) and component scores. Multilinear regression was used to assess the association between change in cPDS, components scores, and dietary pulses, and change in HbA1c over 6-months with age, sex, smoking, baseline HbA1c, BMI, study, and prior CVD event as covariates.
Participants were 62±0.5years of age (mean±standard error), predominantly Caucasian (67%) and South Asian (16%) with a baseline BMI of 30.2±0.3kg/m2, HbA1c of 7.1±0.03% and cPDS of 4.1±0.2 points (out of 25). Change in cPDS was significantly associated with change in HbA1c (beta:-0.036% per point, 95% CI:-0.060, -0.011, P= 0.004). A clinically meaningful reduction in HbA1c of 0.3% may be observed with a 9-point increase in cPDS. Of the individual component scores, a 1-point change in nut intake (beta:-0.060%, 95% CI:-0.110, -0.010, P=0.020) and plant protein (beta:-0.091%, 95% CI:-0.168, -0.014, P=0.020) were significantly associated with change in HbA1c. Viscous fibre tended towards significance (P=0.076). A further analysis of plant protein intake to explore dietary pulse intake, a particularly LGI food, revealed change in dietary pulse intake was significantly associated with change in HbA1c (beta:-0.17% per 1-cup cooked pulses (226g ), 95% CI-0.348, -0.002, P=0.048).

Conclusion: A Portfolio dietary pattern was associated with a reduction in HbA1c in T2DM over a 6-month period, which was predominantly driven by two components: nuts and plant protein, including dietary pulses. The Portfolio Diet may be another dietary pattern suitable in recommendations for glycemic control in adults with T2DM, however, a trial demonstrating the direct causal effect is warranted.