The validity of cost-effectiveness analyses of tight glycemic control. A systematic survey of economic evaluations of pharmacological interventions in patients with type 2 diabetes.

PURPOSE: Currently available randomized trial evidence has shown no reductions in type 2 diabetes (T2D) complications important to patients with tight glycemic control. Yet, economic analyses consistently find tight glycemic control to be cost-effective. To understand this apparent paradox, we systematically identified and appraised economic analyses of tight glycemic control for T2D. METHODS: We searched multiple databases from January 2016 to January 2018 for cost-effectiveness or cost-utility analyses of any glucose-lowering treatments for adults with T2D using simulations with long-40 years to lifetime-time horizons. Reviewers selected and appraised each study independently and in duplicate with good reproducibility. RESULTS: We found 30 analyses, most comparing the glycemic impact of glucose-lowering drugs and applying their impact on HbA1c to model (most commonly IMS CORE or Cardiff T2DM) their impact on the incidence of diabetes-related complication. Models drew from observational evidence of the correlation of HbA1c levels and diabetes-related complication rates; none used estimates of the effect of lowering HbA1c on these outcomes from systematic reviews of randomized trials. Sensitivity analyses, when conducted, demonstrate substantial loss of cost-effectiveness as simulations approach the results seen in these trials. CONCLUSIONS: Reliance on the association between glycemic control and diabetes-related complications evident in observational studies but not apparent in randomized trial bias the estimates of the cost-effectiveness of interventions to improve glycemic control.

Antibodies against glutamic acid decarboxylase and indices of insulin resistance and insulin secretion in nondiabetic adults: a cross-sectional study.

BACKGROUND: Autoimmunity against insulin-producing beta cells from pancreatic islets is a common phenomenon in type 1 diabetes and latent autoimmune diabetes in adults. Some reports have also related beta-cell autoimmunity to insulin resistance (IR) in type 2 diabetes. However, the extent to which autoimmunity against components of beta cells is present and relates to IR and insulin secretion in nondiabetic adults is uncertain. AIM: To explore the association between antibodies against glutamic acid decarboxylase (GADA), a major antigen from beta cells, and indices of whole-body IR and beta-cell capacity/insulin secretion in adults who do not have diabetes. METHODS: We studied 81 adults of both sexes aged 30-70, without known diabetes or any autoimmune disease. Participants underwent an oral glucose tolerance test (OGTT) with determination of plasma glucose and insulin at 0, 30, 60, 90, and 120 minutes. From these results we calculated indices of insulin resistance (homeostasis model assessment of insulin resistance [HOMA-IR] and incremental area under the insulin curve [iAUCins]) and insulin secretion (corrected insulin response at 30 minutes and HOMA beta-cell%). GADAs were measured in fasting plasma using immunoenzymatic methods. RESULTS: We found an overall prevalence of GADA positivity of 21.3%, without differences by sex and no correlation with age. GADA titers did not change monotonically across quartiles of any of the IR or insulin secretion indices studies. GADA did not correlate linearly with fasting IR expressed as HOMA-IR (Spearman's r=-0.18, p=0.10) or postabsorptive IR expressed as iAUCins (r=-0.15, p=0.18), but did show a trend toward a negative correlation with insulin secretory capacity expressed by the HOMA-beta cell% index (r=-0.20, p=0.07). Hemoglobin A1c, body mass index, and waist circumference were not associated with GADA titers. CONCLUSION: GADA positivity is frequent and likely related to impaired beta-cell function among adults without known diabetes.