OBJECTIVEIn this randomized controlled trial we evaluated the effect of registered dietitian–led management of diabetes on glycemic control and macronutrient intake in type 2 diabetic patients in primary care clinics in Taiwan and studied the association between changes in macronutrient intake and glycemic measures.RESEARCH DESIGN AND METHODSWe recruited 154 adult patients with type 2 diabetes and randomly assigned them to a routine care control group (n = 79) or a registered dietitian–led intervention group (n = 75) who received on-site diabetic self-management education every 3 months over 12 months.RESULTSOver the 1-year period, neither the intervention group (n = 75) nor the control group (n = 79) had significant changes in A1C, whereas the intervention patients with poorly controlled baseline A1C (≥7%) (n = 56) had significantly greater improvements in A1C and fasting plasma glucose than the control subjects (n = 60) (−0.7 vs. −0.2%, P = 0.034; −13.4 vs. 16.9 mg/dl, P = 0.007) during the same period. We also found significant net intervention-control group differences in overall energy intake (−229.06 ± 309.16 vs. 56.10 ± 309.41 kcal/day) and carbohydrate intake (−31.24 ± 61.53 vs. 7.15 ± 54.09 g/day) (P < 0.001) in patients with poorly controlled A1C. Multivariable adjusted modeling revealed an independent association between changes in carbohydrate intake and A1C in the intervention group (n = 56; β = 0.10, SEM = 0.033, P = 0.004).CONCLUSIONSOn-site registered dietitian–led management of diabetes can improve glycemic control in patients with poorly managed type 2 diabetes in primary care clinics in Taiwan. A reduction in carbohydrate intake may improve glycemic status.