Mazze R et al. - This review addresses the association between HbA1c and mean blood glucose and their relationship to diurnal glucose patterns. Relying solely on HbA1c or a "derived" mean glucose may be misleading, providing "false impressions" of therapeutic efficacy. Consequently, because self-monitoring provides a unique vantage point from which to view diurnal glucose patterns it remains a potent component of the armamentarium of diabetes management.