After many years of frustratingly limited success, the genetic architecture of Type 2 diabetes is finally being uncovered. Recent genome-wide association studies have identified novel genes predisposing to Type 2 diabetes, which are giving fascinating new insights into the pathophysiology of this complex disease. Of the genes so far identified by this approach, one stands out as having by far the biggest effect on disease risk. A common variant of TCF7L2, when present in two copies, is associated with an approximate 2-fold higher risk of Type 2 diabetes. This short review focuses on the TCF7L2 finding and discusses its significance for Type 2 diabetes genetic studies and for clinical practice.