Effects of long term treatment with metformin on clinical, metabolic and endocrine parameters in women with polycystic ovary syndrome and increased metabolic risk

Uvod: Sindrom policističnih jajčnikov (angl. polycystic ovary syndrome – PCOS) je najpogo-stejša endokrina motnja pri ženskah v rodni dobi. Značilnosti PCOS so hiperandrogenizem, kronične anovulacije in presnovne motnje, med katerimi je poglavitna insulinska rezistenca. Temeljno zdravilo za vse bolnice s PCOS in indeksom telesne mase (ITM) ? 25 kg/m2 je metformin, s katerim zmanjšujemo presnovne zaplete in uredimo menstrualne cikluse. Zaradi pomanjkanja rezultatov dolgoročnih raziskav ni jasnih priporočil, kako dolgo je potrebno in smiselno zdravljenje z metforminom pri bolnicah s PCOS in ITM ? 25 kg/m2, pri katerih je glukozna toleranca normalna, z zdravljenjem pa dosežemo normalne menstruacijske cikluse in stabilno telesno maso. Prav tako ni znano, kakšne so posledice ukinitve metformina in kako hitro izzvenijo njegovi učinki. Metode: Zastavili smo raziskavo iz treh delov. V prvem, retrospektivnem delu smo proučili učinke dolgoletnega zdravljenja bolnic s PCOS z metforminom s pregledom zdravstvene do-kumentacije za obdobje 10 let. V drugem delu smo opravili prospektivno raziskavo, v kateri smo primerjali posledice nadzorovane ukinitve zdravljenja z metforminom pri predhodno kratkotrajno (KT) in dolgotrajno (DT) zdravljenih z metforminom prekomerno težkih bolnic s PCOS in normalno glukozno toleranco. KT-skupina je bila z metforminom predhodno zdrav-ljenja v povprečju 1,03 ± 0,13 leta, DT-skupina pa 5,07 ± 2,52 let. Proučevali smo posledice šestmesečne prekinitve zdravljenja na telesno maso, rednost menstrualnih ciklov ter na pre-snovne in endokrine dejavnike. V tretjem delu smo pri delu bolnic iz drugega dela opravili biopsijo podkožnega maščevja za določitev izražanja mRNA insulinskega receptorja (INSR), substrata insulinskega receptorja-1 (IRS-1) in SLC2A4 (GLUT-4) ter primerjali posledice pre-kinitve zdravljenja z metforminom na izražanje mRNA receptorjev in prenašalcev insulinske signalne poti. Rezultati: V prvem letu zdravljenja z metforminom se je telesna masa znižala za 3,9 ± 6,8 kg (p < 0,001). Število menstruacij na leto se je v prvem letu povečalo s 7,6 ± 3,8 na 10,8 ± 2,7 (p < 0,001), kasneje pa celo do 11 menstruacij na leto. Celokupni testosteron in androstendion sta se po prvem letu znižala za 15,4 ± 47,9 % oziroma 11,3 ± 46,4 %. Pri večini bolnic, ki so nadaljevale z zdravljenjem, smo med nadaljnjim spremljanjem opažali vzdrževanje stabilnega kliničnega, presnovnega in endokrinega stanja. Stopnja napredovanja iz normoglikemije v motnje glukozne homeostaze je bila ob zdravljenju z metforminom nizka. Osip vzorca je bil z vsakim letom večji, po 3 letu zdravljenja preko 50 %. Šest mesecev po ukinitvi metformina se je bolnicam iz KT-skupine telesna masa povečala povprečno za 4 kg (p = 0,019). Pogostost menstrualnega cikla se je zmanjšala v DT-skupini (p = 0,027). Viden je bil le mejni porast vrednosti androstendiona v obeh skupinah. V analizi izražanja mRNA INSR, IRS-1 in SLC2A4 (GLUT-4) je bila edina značilna spre-memba v šestmesečnem opazovanem obdobju po ukinitvi metformina izražanje mRNA IRS-1 celotne in DT-skupine, ki je značilno upadlo (p = 0,04 in p = 0,013). Po 6 mesecih je bila vidna povezava izražanja mRNA SLC2A4 (GLUT-4) s telesno maso, ITM, obsegom pasu, označevalci maščobnega tkiva, lipidograma, glukoze med oralnim glukoznim tolerančnim testom, oceno homeostatske insulinske rezistence (HOMA-IR) in insulinogenim indeksom. Zaključek: Z retrospektivnim delom raziskave smo ugotovili, da je dolgoletno zdravljenje z metforminom pri prekomerno težkih in debelih bolnicah s PCOS in normalno homeostazo glukoze povzročilo največji klinično merljivi učinek zdravljenja v prvem letu zdravljenja. Pri večini bolnic, ki so nadaljevale z zdravljenjem, smo med nadaljnjim spremljanjem opažali vzdrževanje stabilnega stanja. Sodelovanje je vsako leto upadalo, zlasti od tretjega leta zdrav-ljenja dalje. Visok osip bi lahko v klinični praksi zmanjšali s stalnim osveščanjem o realnih ciljih in koristih dolgoročnega zdravljenja. V drugem in tretjem delu raziskave smo ugotovili, da je napredovanje PCOS in z njim povezanih zapletov po ukinitvi zdravljenja z metforminom deloma odvisno od trajanja zdravljenja pred ukinitvijo in da je 6 mesecev po ukinitvi še pri-sotna presnovna zapuščina predhodnega zdravljenja. Nadzorovana ukinitev zdravljenja z metforminom pri prekomerno težkih bolnicah s PCOS z normalno glukozno homeostazo je 6 mesecev po ukinitvi povzročila povečanje telesne mase v KT-skupini, zmanjšala število men-strualnih krvavitev in mejno zvišala vrednosti androstendiona v DT-skupini. V obeh skupinah smo 6 mesecev po ukinitvi zdravljenja z metforminom opazovali nespremenjeno količino visceralnega maščevja, nespremenjeno insulinsko občutljivost, stabilno glukozno homeostazo in stabilno izražanje mRNA SLC2A4 (GLUT-4) v podkožnem maščevju.Background: Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women in reproductive age. It is defined by hyperandrogenism, chronic anovulation and me-tabolic disorders, among which the main is insulin resistance. Metformin is the basic drug for all patients with PCOS and body mass index (BMI) ⡥ 25 kg/m2, which reduces metabolic complications and regulates menstrual cycles. Due to the lack of long-term research data, there are no clear recommendations on duration and appropriate of metformin treatment in patients with PCOS and BMI ⡥ 25 kg/m2, with normal glucose homeostasis and when treat-ment achieves normal menstrual cycles and stable body weight. It is unknown what are the consequences of metformin withdrawal and how quickly its effects subside. Methods: We set up a three-part survey. In the first retrospective part we examined the effects of long-term treatment with metformin of patients with PCOS by reviewing medical records for a period of 10 years. In the second part, we conducted a prospective study com-paring the consequences of controlled metformin withdrawal in previously short-term (ST) and long-term (LT) metformin-treated overweight patients with PCOS and normal glucose tolerance. The ST group had been treated with metformin for an average of 1.03 ± 0.13 years and the LT group for 5.07 ± 2.52 years. We studied the effects of 6-month treatment withdrawal on body weight, regularity of menstrual cycles, metabolic and endocrine factors. In the third part subcutaneous fat biopsy was performed in some patients to determine the insulin receptor (INSR), insulin receptor-1 substrate (IRS-1) and SLC2A4 (GLUT-4) mRNA expression. We compared the effects of metformin discontinuation and expression of substra-tes of the insulin signaling pathway mRNA. Results: In the first year of metformin treatment body weight decreased by 3.9 ± 6.8 kg (p < 0.001). The number of menstrual periods per year increased from 7.6 ± 3.8 to 10.8 ± 2.7 in the first year (p < 0.001) and later even to 11 menstrual periods/year. Total testosterone and an-drostenedione decreased by 15.4 ± 47.9 % and 11.3 ± 46.4 % respectively after the first year. In most patients who continued treatment maintenance of a stable clinical, metabolic and en-docrine status was observed during follow-up. The rate of progression from normoglycaemia to impaired glucose homeostasis was low with metformin treatment. The sample dropout in-creased with each year to over 50 % after 3 years of treatment. Six months after metformin withdrawal patients in the ST group gained an average of 4 kg body weight (p = 0.019). The frequency of the menstrual cycle decreased in the LT group (p = 0.027). Only a marginal increase in androstenedione values was seen in both groups. In the analysis of INSR, IRS-1 and SLC2A4 (GLUT-4) mRNA expression the only signifi-cant change was 6 months after metformin withdrawal in IRS-1 mRNA expression in whole and LT groups, which significantly decreased (p = 0.04 and p = 0.013). After 6 months, the association of SLC2A4 (GLUT-4) mRNA expression with body weight, BMI, waist circum-ference, adipose tissue parameters, lipidogram, glucose in oral glucose tolerance test, homeo-static model assessment for insulin resistance (HOMA-IR) and insulinogenic index is visible. Conclusion: A retrospective part of the study found that long-term metformin treatment in overweight and obese patients with PCOS and normal glucose homeostasis resulted in the greatest clinically measurable treatment effect in the first year after initiation of treatment. Steady state was observed in most patients who continued treatment during follow-up. Adhe-rence decreased every year, especially from the third year of treatment onwards. The high dropout rate could be reduced in clinical practice by continuous awareness of the realistic goals of treatment and the benefits of long-term treatment. In the second and third parts of the study, we found that the progression of PCOS and related complications after metformin withdrawal was partly dependent on the duration of treatment before withdrawal and that a metabolic legacy of prior treatment was still present 6 months after metformin withdrawal. Controlled metformin withdrawal in overweight patients with PCOS and normal glucose ho-meostasis resulted in weight gain in the ST group 6 months after withdrawal, decreased frequency of menstrual bleeding and marginally increased androstenedione levels in the LT group. In both groups, unchanged visceral fat, unchanged insulin sensitivity, stable glucose homeostasis, and stable subcutaneous fat mRNA expression (GLUT-4) were observed 6 months after withdrawal of metformin therapy