The effect of glucose variability on the risk of microvascular complications in type 1 diabetes: response to Kilpatrick et al. - Monnier L; Colette C; Leiter L; Ceriello A; Hanefeld M; Owens D; Tajima N; Tuomiletho J; Davidson J; Service FJ; O'Brien PC; Hirsch IB; et al. (Diabetes Care, 2007)