White, Neil H.

OBJECTIVE During the Diabetes Control and Complications Trial (DCCT), intensive diabetes therapy achieving a mean HbA1c of ∼7% was associated with a threefold increase in the rate of severe hypoglycemia (defined as requiring assistance) compared with conventional diabetes therapy with a mean HbA1c of 9% (61.2 vs. 18.7 per 100 patient-years). After ∼30 years of follow-up, we investigated the rates of severe hypoglycemia in the DCCT/Epidemiology of Diabetes Inverventions and Complications (EDIC) cohort. RESEARCH DESIGN AND METHODS Rates of severe hypoglycemia were reported quarterly during DCCT and annually during EDIC (i.e., patient recall of episodes in the preceding 3 months). Risk factors influencing the rate of severe hypoglycemia over time were investigated. RESULTS One-half of the DCCT/EDIC cohort reported episodes of severe hypoglycemia. During EDIC, rates of severe hypoglycemia fell in the former DCCT intensive treatment group but rose in the former conventional treatment group, resulting in similar rates (40.8 vs. 36.6 episodes per 100 patient-years, respectively) with a relative risk of 1.12 (95% CI 0.91–1.37). A preceding episode of severe hypoglycemia was the most powerful predictor of subsequent episodes. Entry into the DCCT study as an adolescent was associated with an increased risk of severe hypoglycemia, whereas insulin pump use was associated with a lower risk. Severe hypoglycemia rates increased with lower HbA1c similarly among participants in both treatment groups. CONCLUSIONS Rates of severe hypoglycemia have equilibrated over time between the two DCCT/EDIC treatment groups in association with advancing duration of diabetes and similar HbA1c levels. Severe hypoglycemia persists and remains a challenge for patients with type 1 diabetes across their life span.

Abstract Congenital generalized lipodystrophy (CGL) is a rare autosomal recessive disorder characterized by near complete absence of adipose tissue from birth. Recently, mutations in 1-acylglycerol-3-phosphate O-acyltransferase 2 (AGPAT2) and Berardinelli-Seip congenital lipodystrophy 2 (BSCL2) genes were reported in pedigrees linked to chromosomes 9q34 and 11q13, respectively. There are limited data regarding phenotypic differences between the various subtypes of CGL. Furthermore, whether there are additional loci for CGL remains unknown. Therefore, we genotyped 45 pedigrees with CGL for AGPAT2 and BSCL2 loci and compared the phenotypes in the various subtypes. Twenty-six pedigrees harbored mutations, including seven novel variants, in the AGPAT2 gene, and 11 pedigrees harbored mutations in the BSCL2 gene, including five novel variants. Eight pedigrees had no substantial alterations in either gene. Of these, three informative pedigrees showed no linkage to markers spanning the AGPAT2 and BSCL2 loci, and in six of the affected subjects, the transcripts of AGPAT2 and BSCL2 were normal. All subtypes of CGL showed high prevalence of diabetes, hypertriglyceridemia, and acanthosis nigricans. However, patients with BSCL2 mutations had lower serum leptin levels, an earlier onset of diabetes, and higher prevalence of mild mental retardation compared with other subtypes. We conclude that besides AGPAT2 and BSCL2, there may be additional loci for CGL. The genetic heterogeneity in CGL patients is accompanied by phenotypic heterogeneity.