Comment on: Nathan DM, Buse JB, Davidson MB et al (2006) Management of hyperglycaemia in type 2 diabetes: a consensus algorithm for the initiation and adjustment of therapy. A consensus statement from the American Diabetes Association and the European Association for the Study of Diabetes. Diabetologia 49:1711-1721.

To the Editor: The consensus statement from the American Diabetes Association and the European Association for the Study of Diabetes, published in both Diabetologia [1] and Diabetes Care [2], included the following statement concerning the incidence of hypoglycaemia in insulintreated type 2 diabetes: ‘In clinical trials aimed at normoglycaemia and achieving a mean HbA1c of ∼7%, severe hypoglycaemic episodes (defined as requiring help from another person to treat) occurred at a rate of between 1 and 3 per 100 patient-years ....’ This is not a balanced description of the published literature. The authors cited five publications to support the statement quoted [3–7]. However, two of these do not include event rates for severe hypoglycaemia as defined in the statement [5, 6] and one was a review with no original data [7]. Notably, the latter review cited studies reporting event rates for severe hypoglycaemia in insulin-treated type 2 diabetic patients of 28 and 35 per 100 patient-years [7], which are well in excess of ‘between 1 and 3 per 100 patient-years’ [1, 2]. Thus, only two [3, 4] of the five publications cited, involving 127 patients with insulin-treated type 2 diabetes, support the authors’ statement (Table 1). The authors did not cite original publications reporting severe hypoglycaemia event rates of 10 [8], 28 [9], 35 [10], 44 [11] and 73 [12] per 100 patient-years, involving 907 patients with insulin-treated type 2 diabetes (Table 1). (Admittedly, one [11] was published at about the same time as the consensus statement.) These five reports included a prospective study of a population-based random sample of patients with insulin-treated type 2 diabetes that found a severe hypoglycaemia event rate of 35 per 100 patient-years [10]. These severe hypoglycaemia event rates, ranging from 10–73 per 100 patient-years, in insulin-treated type 2 diabetes [8–12] approach those in type 1 diabetes, which range from 62–170 per 100 patient-years [10, 12–14] (Table 1). Furthermore, the authors did not cite additional population-based data in which the event rates for severe hypoglycaemia requiring emergency medical treatment in insulin-treated type 2 diabetes ranged from 40–100% [15, 16] of those in type 1 diabetes. The barrier of hypoglycaemia precludes maintenance of euglycaemia over a lifetime of diabetes and thus full realisation of the now well-established vascular benefits of glycaemic control [17]. In contrast to type 1 diabetes, hypoglycaemia is relatively infrequent early in the course of type 2 diabetes when glucose counter-regulatory defences against falling plasma glucose concentrations are intact [17, 18]. However, as discussed here and summarised in Table 1, there is a body of evidence—including prospective, population-based data—indicating that hypoglycaemia becomes progressively more frequent, approaching the incidence rate seen in type 1 diabetes, as patients approach the insulin-deficient end of the spectrum of type 2 diabetes, where physiological and behavioural defences against falling glucose levels become compromised [17, 18]. I quite agree with the authors of the consensus statement that insulin is the most effective of diabetes medications in Diabetologia (2007) 50:222–224 DOI 10.1007/s00125-006-0448-4