Introduction and Objective: Asian Indians have increased insulin resistance, more rapid β-cell decline & higher T2D risk. Early interventions targeting these factors can prevent T2D. We compared the effects of a low carbohydrate, low saturated fat (LC) diet to a high unrefined carbohydrate, low fat (HC) diet on β-cell function, insulin sensitivity & fat distribution in Asian Indians with prediabetes.Methods: 53 Asian Indians with prediabetes by ADA criteria (58% males; mean[SD] age 40[6] yrs; BMI 30.4[3.1] kg/m2; fasting glucose 5.7[0.6] mmol/L; 2h postprandial glucose, 2hPG 9.3[2.3] mmol/L) were randomized to a hypocaloric LC diet (20% energy from carbohydrate, 30% protein, 50% fat [<10% saturated fat]) or energy-matched HC diet (50% carbohydrate, 20% protein, 30% fat [<10% saturated fat]), combined with aerobic & resistance exercise 3h/wk for 24 weeks. OGTTs at week 0, 8 and 24 assessed insulin sensitivity (Matsuda ISI) and secretion (Insulinogenic Index, IGI) from 0-30min incremental C-peptide/glucose to derive β-cell function corrected for prevailing insulin sensitivity (Disposition Index, DI). Body composition was measured by MRI, MRS & DXA.Results: 40 participants (LC 22, HC 18) completed the study. Compared to HC, LC had greater increases in DI (EMM[95%CI]; LC 474[294,655], HC 239[47,431], p=0.03) and ISI (LC 3.5[2.0,4.9], HC 1.7 [0.1,3.2], p=0.04), and reductions in fasting insulin (LC -7.8[-10.6,-5], HC -4.1[-6.9,-1.2] mU/L, p=0.045) and glucose (LC -0.5[-0.8,-0.2], HC-0.4 [-0.7,-0.1] mmol/L, p=0.05). LC lowered weight (LC -9.7[-12.3,-7.1], HC -6.5[-9.2,-3.7] kg, p=0.01), liver fat (LC -9.5[-13,-6], HC -6.5[-10.1,-2.9] %, p<0.001) and subcutaneous abdominal fat (LC -1328[-1695,-961], HC -892[-1279,-504] cc, p=0.03) more than HC. VAT, IMCL, IMAT, pancreatic fat, 2hPG, blood pressure & lipids fell similarly in both groups (p≥0.18).Conclusion: In Asian Indians, LC improved β-cell function & insulin sensitivity, highlighting its superiority for T2D prevention.
J. Tay: None. G.D. Brinkworth: None. S. Sendhil Velan: None. C. Khoo: None. S. Sadananthan: None. B. Gower: None. C.H. Thompson: None.
National Medical Research Council, Ministry of Health, Singapore (MOH-000322-00 and MOH-000858-00); the Agency for Science, Technology and Research, Singapore (C220314028); and the Almond Board of California, US (DIA-19-TAYJ-NR-01)
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