Limited Value of the Homeostasis Model Assessment to Predict Insulin Resistance in Older Men With Impaired Glucose Tolerance

Abstract

A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances. Limited Value of the Homeostasis Model Assessment to Predict Insulin Resistance in Older Men With Impaired Glucose Tolerance O R I G I N A L A R T I C L EOBJECTIVE -Insulin resistance (IR) in older individuals is associated with risk factors for coronary artery disease. The glucose clamp measures IR directly, but the homeostasis model assessment (HOMA) of IR, referred to here as HOMA-IR, is based on fasting glucose and insulin and is less invasive and labor intensive. This method requires validation in the elderly. RESEARCH DESIGN AND METHODS -We assessed the validity of HOMA-IR as an index of IR by comparing it to glucose infusion rates (GIRs) measured by a glucose clamp (600 pmol и m Ϫ2 и min Ϫ1 ) in 45 obese men (61 ± 8 years of age, mean ± SD) with normal glucose tolerance (NGT) (n = 21) or impaired glucose tolerance (IGT) (n = 24). We also evaluated relationships between body composition, exercise capacity, and IR.RESULTS -Subjects with NGT had lower BMI (28 ± 3 vs. 31 ± 3 kg/m 2 ), waist circumference (97 ± 9 vs. 105 ± 9 cm), waist-to-hip ratio (WHR) (0.93 ± 0.06 vs. 0.97 ± 0.05), and percent body fat (25 ± 6 vs. 30 ± 6) than subjects with IGT. Subjects with NGT also had lower areas above basal during the 2-h oral glucose tolerance test for glucose (274 ± 95 vs. 419 ± 124 mmol и min/l) and insulin (38,142 ± 18,206 vs. 58,383 ± 34,408 pmol и min/l) and lower HOMA-IR values (2.2 ± 0.8 vs. 4.2 ± 2.6) than subjects with IGT. GIR (µmol и kg -1 FFM и min -1 ) was higher in subjects with NGT than in subjects with IGT (53 ± 11 vs. 43 ± 14). HOMA-IR correlated with GIR in subjects with NGT (r = Ϫ0.59), but not in subjects with IGT (r = Ϫ0.13). GIR correlated with VO 2max in subjects with NGT (r = 0.58) and IGT (r = 0.42), but with WHR only in subjects with NGT (r = Ϫ0.53). HOMA-IR correlated with VO 2max (r = Ϫ0.57) and waist circumference (r = 0.54) in subjects with NGT, but with percent body fat in subjects with IGT (r = 0.54).CONCLUSIONS -These findings indicate that HOMA-IR should not be used as an index of IR in older individuals who may be at risk for IGT, and suggest that lifestyle changes that increase VO 2max and decrease body fat may reduce IR in older people.

Birthweight of offspring and paternal insulin resistance and paternal diabetes in late adulthood: cross sectional survey

“…Information on prevalent diabetes was based on review of general practice medical records between initial screening in 1978 to 1980 and the return of Q20, and also on recall by the subject of physician-diagnosed diabetes (obtained by completion of Q20). Insulin resistance was estimated according to the homeostasis model assessment (HOMA) as the product of fasting glucose (mmol/l) and insulin (µU/ml) divided by the constant 22.5 [21]. HOMA scores were not calculated for diabetic men and men with fasting glucose above 7 mmol/l, because in a study of older men (mean age 61 years) HOMA scores in men with glucose intolerance or diabetes were only weakly correlated with euglycaemic clamp assessment (r s =0.13) [21].…”

“…Insulin resistance was estimated according to the homeostasis model assessment (HOMA) as the product of fasting glucose (mmol/l) and insulin (µU/ml) divided by the constant 22.5 [21]. HOMA scores were not calculated for diabetic men and men with fasting glucose above 7 mmol/l, because in a study of older men (mean age 61 years) HOMA scores in men with glucose intolerance or diabetes were only weakly correlated with euglycaemic clamp assessment (r s =0.13) [21]. Men with a doctor's diagnosis of diabetes (GP reporting at any of the biennial record reviews or recall at any of the questionnaire surveys) and men with a fasting glucose above 7 mmol/l were all considered to have prevalent diabetes in this study [22].…”

Prevalence of Insulin Resistance Syndrome in Southwestern France and Its Relationship With Inflammatory and Hemostatic Markers

“…In this study and to allow for further comparisons, we chose to define IRS according to the World Health Organization recommendations (1,14). Furthermore, although its reliability among older obese subjects has been questioned (17), HOMA provides a useful model to assess insulin resistance and ␤-cell function in epidemiological studies in which only fasting samples are available (18). It is also a reliable marker of insulin resistance for assessment and follow-up of patients with diabetes (19).…”

Do reproductive hormones modify insulin sensitivity and metabolism in older men? A randomized, placebo-controlled clinical trial of recombinant human chorionic gonadotropin

“…Homeostasisdetermined insulin sensitivity has been validated in a wide population of obese and nonobese individuals of various ages (54), including those with diabetes mellitus (58) and particularly in older men (59).…”