Flow chart of study selection. ADA = American Diabetes Association, DAHTA = Deutsche Agentur für Health Technology Assessment, DARE = National Health Service's Database of Abstracts of Reviews of Effects, DDG = Deutsche Diabetes Gesellschaft, EASD = European Association for the Study of Diabetes, GLA = Insulin glargine, GMS = German Medical Science, ISPOR = International Society for Pharmacoeconomics and Outcomes Research, NHS-EED = National Health Service Economic Evaluation Database, NHS-HTA = National Health Service Health Technology Assessment Database, NPH = Neutral Protamine Hagedorn insulin.