Sagittal Abdominal Diameter Is a Strong Anthropometric Marker of Insulin Resistance and Hyperproinsulinemia in Obese Men ULF RIS ´ ERUS, MMED, PHD 1 JOHAN A ¨ RNL ¨ OV, MD, PHD 1 KERSTIN BRISMAR, MD, PHD 2 BJ ¨ ORN ZETHELIUS, MD, PHD 1 LARS BERGLUND, BSC 3 BENGT VESSBY, MD, PHD 1 OBJECTIVE — It is clinically important to find noninvasive markers of insulin resistance and hyperproinsulinemia because they both predict cardiovascular and diabetes risk. Sagittal ab- dominal diameter (SAD) or “supine abdominal height” is a simple anthropometric measure previously shown to predict mortality in men, but its association with insulin resistance and hyperproinsulinemia is unknown. RESEARCH DESIGN AND METHODS — In a common high-risk group of 59 moder- ately obese men (aged 35– 65 years, BMI 32.6  2.3 kg/m 2 ), we determined anthropometry (SAD, BMI, waist girth, and waist-to-hip ratio [WHR]); insulin sensitivity (euglycemic- hyperinsulinemic clamp); and plasma concentrations of intact proinsulin, specific insulin, C- peptide, glucose, and serum IGF binding protein-1 (IGFBP-1). To compare SAD with other anthropometric measures, univariate and multiple regression analyses were used to determine correlations between anthropometric and metabolic variables. RESULTS — SAD showed stronger correlations to all measured metabolic variables, including insulin sensitivity, than BMI, waist girth, and WHR. SAD explained the largest degree of variation in insulin sensitivity (R 2 = 0.38, P  0.0001) compared with other anthropometric measures. In multiple regression analyses, including all anthropometric measures, SAD was the only inde- pendent anthropometric predictor of insulin resistance (P  0.001) and hyperproinsulinemia (P  0.001). CONCLUSIONS — In obese men, SAD seems to be a better correlate of insulin resistance and hyperproinsulinemia (i.e., cardiovascular risk) than other anthropometric measures. In overweight and obese individuals, SAD could represent a simple, cheap, and noninvasive tool that could identify the most insulin resistant in both the clinic and clinical trials evaluating insulin sensitizers. These results need confirmation in larger studies that also include women and lean subjects. Diabetes Care 27:2041–2046, 2004 M ore than half of adult Americans are overweight or obese (1). Many, but far from all of those subjects, will suffer from obesity-related diseases. Insulin resistance may be the key factor in obesity that contributes to increased health risk, as the more insulin resistant an individual, the more likely they are to develop diabetes and cardio- vascular disease (2– 4). Therefore, identi- fication of insulin resistance also is important in moderately obese subjects. Recently, elevated intact proinsulin, reflecting both insulin resistance and -cell dysfunction (5), has emerged as an independent predictor of type 2 diabetes (5–7) and cardiovascular mortality (8,9). However, a simple clinical surrogate marker for hyperproinsulinemia is still to be found. McLaughlin and Reaven (10) recently highlighted the need for a useful tool to identify insulin resistance, as direct mea- sures of insulin resistance are unfeasible for clinical use. While fasting insulin has shown to be a useful estimate of insulin resistance, it is invasive and the lack of standardized assays limits its use (11). Al- ternatively, triglycerides (1.47 mmol/l) could function as a good marker (11). Anthropometric measures have served as noninvasive markers because obesity, particularly abdominal obesity (12), is closely associated with insulin re- sistance. However, studies using direct methods revealed that only 25–50% of all obese nondiabetic and normotensive subjects are clinically significantly insulin resistant (11,13) and that waist girth or waist-to-hip ratio (WHR) was not better than BMI in identifying insulin resistance (13). More recently, “abdominal height” or sagittal abdominal diameter (SAD) has shown to be strongly associated with glu- cose intolerance (14), cardiovascular risk (14 –18), and mortality (19,20) (SAD was divided by thigh girth in the study by Kahn et al. [19]) independently of other anthropometric measures. SAD is also an excellent estimate of visceral fat (21–23), implying that SAD might be a particularly good marker of insulin resistance (12,24). Despite these compelling data, the role of SAD has been overlooked, whereas waist girth has received more attention (14,25,26). Given that insulin resistance is a major health culprit (4), there are sur- ●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●●● From the 1 Clinical Nutrition Research Unit, Department of Public Health and Caring Sciences/Geriatrics, Uppsala University, Uppsala, Sweden; the 2 Department of Molecular Medicine, Karolinska Institute, Stock- holm, Sweden; and the 3 Uppsala Clinical Research Center, Uppsala University, Uppsala, Sweden. Address correspondence and reprint requests to Dr. Ulf Rise ´rus, Churchill Hospital, Oxford Centre for Diabetes, Endocrinology and Metabolism, OX3 7LJ Oxford, U.K. E-mail: ulf.riserus@oxlip.ox.ac.uk. Received for publication 4 December 2003 and accepted in revised form 8 May 2004. Abbreviations: ELISA, enzyme-linked immunosorbent assay; IGFBP-1, IGF binding protein-1; SAD, sagittal abdominal diameter; WHR, waist-to-hip ratio. A table elsewhere in this issue shows conventional and Syste `me International (SI) units and conversion factors for many substances. © 2004 by the American Diabetes Association. Metabolic Syndrome/Insulin Resistance Syndrome/Pre-Diabetes O R I G I N A L A R T I C L E DIABETES CARE, VOLUME 27, NUMBER 8, AUGUST 2004 2041