OBJECTIVE: Many patients with early diabetes remain untreated. Our objectives were to identify clinical predictors of 1) worsening glycemic control and 2) medical treatment initiation in response to worsening glycemic control among patients with type 2 diabetes. RESEARCH DESIGN AND METHODS: We identified 5,804 type 2 diabetic patients seen at least twice between June 2005 and June 2006 within our 12-clinic primary care network. We examined predictors of diabetes progression (A1C >or=7% or initiation of hypoglycemic agent) over a 1-year follow-up period in 705 patients who had A1C <7% and were not on glucose-lowering medications at baseline. In the 200 patients in this group who progressed, we examined predictors of medical therapy initiation. RESULTS: In multivariate analyses, baseline A1C (P < 0.0001), younger age (P = 0.04), and weight gain (P = 0.03) were independent predictors of progression after adjusting for race, sex, and baseline HDL levels. Each decade of increasing age reduced the risk of progression by 15%. Each 1-lb increase in weight was associated with a 2% increased odds of progression. Likelihood of medication initiation among progressors decreased by 40% (P = 0.02) with every decade of age and decreased by 2.3% (P = 0.02) with each 1-mg/dl decrease in LDL level from baseline after adjusting for race, sex, and weight change. CONCLUSIONS: Among untreated primary care patients with type 2 diabetes and A1C <7%, younger patients and those with weight gain were more likely to have diabetes progression and should be the focus of aggressive diabetes management.