Obesity - should we revise indications for treatment with metformin?
BACKGROUND
Treatment of obesity with life style modifications often fails; therefore pharmacological treatment has become a very popular approach. Metformin is one of the examined possibilities. The aim of this study was to verify indications for metformin use in obese women based on metabolic and anthropometric parameters assessed by dual-X-ray absorptiometry (DXA), to establish the degree of insulin resistance and its correlations.


METHODS
Anthropometry, fat measurement by bioimpedance and metabolic profile, including lipids, and oral glucose tolerance test (OGTT) with insulin (0 and 120 min) were performed in 50 female patients diagnosed with simple obesity, aged 18-40 years. Homeostatic model assessment HOMA-R was calculated for insulin resistance, and area under the curve (AUC) for insulin response. Total, android and gynoid fat distribution, and their ratio (A/G), were measured by DXA.


RESULTS
From 50 women who entered the study, 33 were classified as insulin resistant (IR subgroup) and 17 as non-insulin resistant (non-IR subgroup), according to their HOMA-R indices. IR women presented higher waist circumference and DXA A/G ratio. The IR subgroup demonstrated elevated fasting triglycerides and glucose (but in the normal range) and a higher insulin response in OGTT (4.1-fold vs 2.5-fold). From different insulin measurements HOMA index turned out to have the strongest correlations with the metabolic parameters triglycerides and glucose. We found significant positive correlations between android fat and insulin: waist circumference and HOMA-R, WHR and HOMA-R, android fat and HOMA-R, A/G ratio and insulin after OGTT, and A/G ratio and HOMA-R. We found a strong correlation between WHR and A/R ratio.


CONCLUSIONS
67% of premenopausal obese women were insulin resistant. Measures of DXA visceral fat determined by android fat percentage and android/gynoid ratio were the strongest determinants of insulin resistance. Waist-to-hip ratio might be a simple method for determining the indications for metformin treatment.
Department of Internal Medicine, Metabolic Disorders, and Hypertension, University of Medical Sciences, Poznań, Poland.
Magdalena
M
Kujawska-Luczak
Department of Internal and Metabolic Diseases, and Dietetics, University of Medical Sciences, Poznań, Poland.
Hanna
H
Stankowiak-Kulpa
Department of Internal and Metabolic Diseases, and Dietetics, University of Medical Sciences, Poznań, Poland.
Ewelina
E
Swora-Cwynar
Department of Hypertension and Metabolic Disorders, Clinical Hospital No 1, Poznań, Poland.
Katarzyna
K
Musialik
Department of Internal Medicine, Metabolic Disorders, and Hypertension, University of Medical Sciences, Poznań, Poland.
Paweł
P
Bogdański
Department of Human Nutrition and Hygiene, Poznań University of Life Sciences, Poznań, Poland.
Joanna
J
Suliburska
Department of Internal Medicine, Metabolic Disorders, and Hypertension, University of Medical Sciences, Poznań, Poland.
Marian
M
Grzymisławski
dual-energy X-ray absorptiometry; insulin resistance; metformin; oral glucose tolerance test; visceral obesity