Links Between Pharmaceuticals and Diabetes/Obesity
Certain pharmaceutical drugs appear to be able to cause diabetes. Cancer immunotherapy drugs are linked to type 1 diabetes, for example. It is also very clear that drugs can cause weight gain -- insulin is one well-known example.
Some drugs are showing promise in delay the onset of type 1 diabetes in people at high risk of getting the disease, or extending the honeymoon period of better beta cell function.
Type 1 Diabetes
Cancer immunotherapy drugs activate the immune system to attack cancer cells. One problem is that they can also activate the immune system to attack other cells, like the insulin-producing beta cells in the pancreas (these drugs can also cause other autoimmune diseases as well (Ferrari et al. 2019; King et al. 2018; Young et al. 2018), and other endocrine system related diseases (Anderson and Morganstein, 2021; Deligiannis et al. 2021; Deligiorgi et al. 2020). A number of studies have documented cases of type 1 diabetes following or in conjunction with immunotherapy treatment, although the overall incidence is rare (less than 1% of those who take the drugs) (Gauci et al. 2018; Godwin et al. 2017; Venetsanaki et al. 2019). A review identified 283 cases of diabetes following treatment with these drugs between 2014-2018 (Wright et al. 2018). At the Mayo Clinic, over a 6 year period, of 1163 patients who received PD-1 treatment, 12 people developed type 1 diabetes, and 9 experienced a worsening of type 2 diabetes (that's 1.8% total). Diabetes occurred most frequently with pembrolizumab (2.2%) compared with nivolumab (1%) and ipilimumab (0%). The progression to type 1 appears to be quite rapid, and 62% of patients developed additional immune-related problems, especially thyroid disease (Kotwal et al. 2019). However not all people test positive for type 1-related autoimmunity-- only a third, according to one review (Zhang et al. 2020). At UCSD, 0.38% of patients who received immunotherapy (nivolumab or pembrolizumab) developed type 1 diabetes (Yun et al. 2020). According to population-wide data from Japan, being female and having melanoma both increase the risk of developing type 1 diabetes from immunotherapy (Takada et al. 2020).
The New York Times article, The Immune System, Unleashed by Cancer Therapies, Can Attack Organs, discusses how at least 17 people (this was only the beginning of when the issue was recognized) developed acute-onset type 1 diabetes following immunotherapy treatment for cancer.
Some authors have proposed that these patients are developing a distinct form of diabetes, characterized by sudden permanent beta cell failure, but not often associated with autoimmunity or genetic risk of type 1. They are calling it "Checkpoint inhibitor associated autoimmune diabetes mellitus (CIADM)" (Tsang et al. 2019) or "Checkpoint inhibitor-induced insulin-dependent diabetes" (Perdigoto et al. 2019). Some people also get a diabetes that resembles type 2 (Zagouras et al. 2020). Some researchers find that it is different from fulminant type 1 diabetes (Kyriacou et al. 2020). This classification discussion will be something to watch.
As for mechanisms, scientists are trying to figure that out. For example, checkpoint inhibitors seem to target the islets of the pancreas, not just the general pancreas (Zhang et al. 2021).
Nivolumab, an anti PD-1 drug, has been reported to cause acute-onset type 1 diabetes in adults in a number of published case studies (Abdullah et al. 2019; Alzenaidi et al. 2017; Araújo et al. 2017; Capitao et al. 2018; Chokr et al. 2018; Fujui et al. 2019; Gauci et al. 2017; Godwin et al. 2017; Harsch and Konturek 2018; Hatakeyama et al. 2019; Hughes et al. 2015; Keerty et al. 2020; Kumagai et al. 2017; Maekawa et al. 2019; Marshall et al. 2020; Matsuura et al. 2018; Miyauchi et al. 2019; Kikuchi et al. 2021; Miyoshi et al. 2016; Munakata et al. 2017; Okahata et al. 2019; Okamoto et al. 2016; Sakaguchi et al. 2019; Sakurai et al. 2018; Shiba et al. 2018; Takahashi et al. 2018; Takata et al. 2021; Tassone et al. 2018; Teramoto et al. 2017; Tzoulis et al. 2018; Yamamoto et al. 2019; Yilmaz 2019; Zezza et al. 2019), as well as both type 1 diabetes and another autoimmune disease, Graves' disease, in one person (Kurihara et al. 2020). Type 1 diabetes is also reported in one person a few months after nivolumab therapy ended (Mae et al. 2020).
Pembrolizumab, also an anti-PD-1 drug, has also been reported to cause type 1 diabetes (Boyle et al. 2019; de Filette et al. 2019; Edahiro et al. 2019; Gaudy et al. 2015; Hakami et al. 2019; Hughes et al. 2015; Humayun et al. 2016; Kedzior et al. 2021; Kähler et al. 2020; Leentjens et al. 2019; Li et al. 2018; Maamari et al. 2018; Martin-Liberal et al. 2015; Mizab Mellah et al. 2017; Skorpen and Margull, 2019; Smith-Cohn et al. 2017; Tang et al. 2021; Tohi et al. 2019). A review of published case studies finds that pembrolizumab was reported to cause type 1 diabetes in 0.1% of the patients in clinical trials. Of those that did develop diabetes, the average age was 58, in both men and women. Most had melanoma, developed diabetic ketoacidosis, and had at one point taken ipilimumab as well (see below). There was no association found between the number of treatments and the development of diabetes (Cheema et al. 2018). One case study shows how quickly beta cell function declines, with the beta cells completely exhausted within 16 days of hospitalization (Saito et al. 2019).
A 65 year old man with type 2 diabetes and lung cancer, treated with ipilimumab and pembrolizumab, developed very high blood sugar levels and ketoacidosis. It turns out he tested positive for autoantibodies and had no beta cell function, i.e., type 1 diabetes. It appears he developed type 1 diabetes on top of or after type 2 diabetes (Alhusseini and Samantray 2017). Ipilimumab is also linked to fulminant type 1 diabetes, a fast-acting type 1 more common in people of Asian ancestry (Tsiogka et al. 2017). A combination of ipilimumab and nivolumab are also linked to type 1 diabetes (Gunawan et al. 2018; Omodaka et al. 2018; Yamaguchi et al. 2021), including fulminant (autoantibody negative) diabetes in someone over 2 years after starting the drugs (it usually develops in the first 3 months) and over a month after stopping them (Boswell et al. 2021).
Additional anti-PD-1 drugs are also linked to type 1 diabetes, including avelumab (Shibayama et al. 2019) and durvalumab (Mengíbar et al. 2019). In addition, atezolizumab has also led to type 1 diabetes, in a patient who also tested positive for islet antibodies (Honoki et al. 2019) and in an older woman (Nishioki et al. 2020). Two people have developed ketoacidosis and autoantibody-negative diabetes after starting sintilimab as well (Huang et al. 2021; Wen et al. 2020). And also durvalumab (Lopes et al. 2020).
Doctors are wondering if they can predict in advance who might be at risk of developing diabetes after immunotherapy. One lab did a genetic analysis on a patient who took ipilimumab and nivolumab and developed rapid-onset type 1 diabetes (ketoacidosis, positive autoantibodies, no detectable beta cell function). This patient did not have a genetic risk of type 1 diabetes, so genetic testing may not be useful (although larger studies would be helpful here) (Lowe et al. 2016). Further studies are also analyzing if genetic differences may play a role in the response to these drugs (e.g., Matsumura et al. 2018), and if the treatment can be altered to help deal with this problem (Del Rivero et al. 2019), or how to monitor for these effects (Grimmelmann et al. 2021).
These and other case studies have led to the recognition that autoimmunity is one side-effect of immunotherapy, and efforts are underway to limit it (June et al. 2017). Other autoimmune diseases have also been linked to immunotherapy drugs as well (Zitouni et al. 2019). Interestingly, one patient who developed type 1 after immunotherapy tested negative for autoantibodies, but did have immune cell infiltration in his pancreatic islets (Yoneda et al. 2019).
In addition, these drugs can also cause high blood sugar in people who take them, though not to the point of diabetes (Leiter et al. 2020).
Chemotherapy and Other Cancer Treatments
Interferon-α (INF-α) appears to have caused type 1 diabetes in one cancer patient (Sossau et al. 2017).
Acetaminophen and other analgesic antipyretics, including Non-Steroidal Anti-inflammatory Drugs (NSAIDs), taken in the first 2.5 years of life, have been found to not increase the risk of islet autoimmunity by age 6. However, acetaminophen use in children who had a fever was weakly associated with the development of islet autoimmunity by age 3. Acetaminophen use was much more common in the U.S. than in most European countries (Lundgren et al. 2017). A large, population-based study from Norway found that acetaminophen in the prenatal period or early childhood was not associated with the development of childhood T1D (Tapia et al. 2018). Some argue that we should be cautious with regard to type 1 diabetes and acetaminophen (Veteikis 2020; Veteikis 2021). This is something to watch.
A few studies have investigated whether light therapy, i.e., phototherapy, increases the risk of type 1 diabetes. Neonatal phototherapy is used to treat jaundice in newborns. A meta-analysis of 12 published studies found that newborns with jaundice had a slightly increased risk of later developing type 1 diabetes, especially if the jaundice required phototherapy (McNamee et al. 2012). However, a large study from California found no increased risk of type 1 diabetes from neonatal phototherapy (Newman et al. 2016).
A Danish study has found that numerous second-generation (atypical) antipsychotic medications were associated with diabetic ketoacidosis (DKA) and the development of type 1 diabetes (Polcwiartek et al. 2016), as well as DKA and type 2 diabetes (Polcwiartek et al. 2017). One case study describes a 52 year old woman who developed type 1 after taking risperidone for many years. Her blood sugar was 1687 mg/dL when diagnosed! (Hörber et al. 2018).
One of these antipsychotic medications is olanzapine; a case study from Japan describes a 32 year old man who developed acute-onset, autoantibody-positive type 1 diabetes four months after beginning this drug, which was then followed by an extended honeymoon period (Iwaku et al. 2017). This drug is also known for its link to obesity and type 2 diabetes. Exposure to olanzapine in the womb even had metabolic effects on first- and second-generation mice, including glucose intolerance and higher body weight (Courty et al. 2018).
A case study also showed a Japanese man developed type 1 while taking highly active antiretroviral therapy (HAART) for HIV. This appears to be partly due to a gene that is present in Japanese people but not Caucasians (Kamei et al. 2015).
It is well known among people with diabetes that taking steroids will generally increase your blood sugar. In fact, there are even articles on "steroid induced diabetes" (Hwang and Weiss, 2014).
A Danish study found that if pregnant women took steroids, their offspring had a higher risk of developing type 1 diabetes (Greene et al. 2013). Prenatal treatment with dexamethasone, a steroid, causes reduced beta cell function in girls and higher blood glucose levels in those treated (Wallensteen et al. 2020). Also in humans, people who were exposed to dexamethasone in the womb had lower insulin secretion as adults (Riveline et al. 2020). In rats, prenatal treatment with dexamethasone affects pancreatic beta and alpha cells in early postnatal life (Santos-Silva et al. 2020).
A review finds that the steroid betamethosone, which is often given to pregnant women to prevent preterm labor, may affect the risk of autoimmunity and also affect beta cells, thereby affecting the risk of type 1 diabetes (Perna-Barrull et al. 2020)-- although these authors argue that it could act in a preventative way. Prenatal betamethosone protects against diabetes development in non-obese diabetic mice, a mouse model of type 1 diabetes (Perna-Barrull et al. 2019). Yet I think these authors are taking that study too far, as many things that prevent diabetes in NOD mice do not do the same in humans (see the Of Mice, Dogs, and Men page).
Dispensed inhaled asthma drugs, including corticosteroids and β-agonists were associated with an increased risk of type 1 diabetes in a longitudinal nation-wide study of Finnish children. This may help explain why asthma is sometimes found to be a risk factor for type 1 diabetes (Metsälä et al. 2020).
Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS)/ Drug-Induced Hypersensitivity Syndrome (DIHS)
A case study and review finds that while rare, this adverse drug reaction can cause type 1 diabetes (Zhu et al. 2019).
Antibiotics and Other Drugs
A case study describes a woman diagnosed with fulminant (fast-acting) type 1 diabetes following drug-induced hypersensitivity syndrome (DIHS). She also had a virus that has been linked to type 1 diabetes (Takeno et al. 2018).
Thiazide diuretics have been linked to type 1 diabetes in a case study (Perez Fernandez and Feo-Ortega 2020).
Isotretinoin, a drug for severe acne, is linked to type 1 diabetes in one person anyhow (Bozkuş, 2021).
There are a number of studies on antibiotics and type 1 diabetes, discussed on the Diet and the Gut page.
In animals, maternal exposure to psychostimulants (e.g., amphetamine, cocaine, and methamphetamine) during pregnancy permanently impairs the ability of pancreatic beta cells to produce insulin, leading to glucose intolerance in adult female (but not male) offspring. (Korchynska et al. 2019).
Drugs to Prevent or Reverse Type 1 Diabetes
Teplizumab, an anti-CD3 antibody, delayed progression to type 1 diabetes in people at high risk of developing the disease, in a randomized, placebo-controlled, double-blind trial (Herold et al. 2019). The participants were relatives of people with type 1 diabetes (in the TrialNet study) who had tested positive for at least two of the autoantibodies associated with type 1, and had irregular glucose tolerance. This is the first succes33sful prevention trial that I know of for type 1 diabetes in humans! For an editorial commenting on the study, see Traveling down the Long Road to Type 1 Diabetes Mellitus Prevention (Rosen and Ingelfinger 2019). While 43% of the people taking the drug still developed type 1 diabetes, 72% of those who received the placebo developed type 1, and the time to diagnosis was 4 years in the teplizumab group and 2 years in the placebo group. Now the discussion becomes, who should take this drug, when, and how (Dayan et al. 2019). A follow up of this study shows a little about how the drug works-- by stopping the decline in beta cell function, probably via affecting T cells (Sims et al. 2021).
GAD-alum immunotherapy with the drug Diamyd has successfully extended the honeymoon period (preserving beta cell function) in newly diagnosed people with type 1 diabetes with a certain genetic background (Hannelius et al. 2020). However, a trial of Diamyd, plus Etanercept (a drug for autoimmune diseases) and vitamin D, did not find any beneficial results regarding preserving beta cell function (Ludvigsson et al. 2021a). Intralymphatic GAD-alum therapy combined with vitamin D supplementation seemed to preserve beta cell function in people with recent-onset type 1 diabetes with a certain genetic background (Ludvigsson et al. 2021b).
Another drug, fenofibrate, which is used for for reducing triglyceride and cholesterol levels, has been effective in reversing type 1 diabetes in one person at least (and is effective in preventing and reversing diabetes in mice). A published case study describes a 19-year-old woman with classical newly diagnosed type 1 diabetes, which following fenofibrate treatment has been without insulin for 21 months (Buschard et al. 2020).
IL-2, given to children newly diagnosed with type 1 diabetes, appears to help the immune system and preserve some beta cell function in some people (Rosenzwajg et al. 2020). The combination of anti-IL-21 antibody and liraglutide (Victoza) seems to help preserve beta cell function in adults recently diagnosed type 1 diabetes, per a large, international, randomized, double blind, controlled trial. The combination worked better than each drug alone (von Herrath et al. 2021). Also see the commentary about this trial (Long and Speake, 2021).
Additional drugs are also in trials to prevent type 1 diabetes, including oral insulin (Assfalg et al. 2021; Sosenko et al. 2020; Winkler et al. 2019). A systematic review and meta-analysis of all randomized controlled trials of interventions to preserve beta cell function in people newly diagnosed with type 1 diabetes, however, finds that very few have been successful so far (Narendran et al. 2021).
Type 2 Diabetes, Insulin Resistance, and Body Weight
I do not have the time nor inclination to review all the drugs that can cause weight gain, insulin resistance, or even type 2 diabetes here. There are a few lessons we can learn from some of them, however.
Diethylstilbestrol (DES), was a drug given to pregnant women decades ago to prevent miscarriage (it didn't work, but instead led to various health problems in these women's offspring, and now their grandchildren as well). As an estrogen, DES is thought to act similarly to endocrine disrupting chemicals. Fetuses are most vulnerable to its effects, and outcomes may not appear until adulthood. DES is strongly linked to vaginal cancer and adverse reproductive outcomes in offspring. Prenatal exposure to DES may also be linked to other health outcomes, including diabetes, cardiovascular disease, high blood pressure, and high cholesterol (the association with diabetes was not statistically significant, but the risk was higher) (Troisi et al. 2013). Prenatal DES exposure is also linked to slightly increased weight gain in adulthood (Hatch et al. 2015). Prenatal DES exposure is also linked to coronary artery disease and heart attacks, but not strokes (Troisi et al. 2018).
Prenatal DES exposure was linked to an increased risk of pancreatic disorders, including pancreatitis, in women and men. The data also suggested elevated pancreatic cancer risk in DES-exposed women, but not in exposed men. DES was not associated with type 2 diabetes, however (Troisi et al. 2020).
There is some limited evidence linking autoimmunity and DES in humans: women exposed to DES in utero seem to have a higher incidence of autoimmune disease, but only when various autoimmune diseases are grouped together (Ahmed et al. 1999). Yet a more recent study that followed these women over 25 years found that there was not an overall increase in autoimmune diseases in DES exposed daughters, although type 1 diabetes was not included in this study (only four autoimmune diseases were included). However, there was an increased risk of the autoimmune disease rheumatoid arthritis in women under 45, and a lower risk in those over 45 (Strohsnitter et al. 2010).
In animals, when female mice were exposed to a low dose of DES in the first five days of life, they gained more weight by six months of age than mice who were not exposed (Newbold et al. 2009). DES promotes the formation of fat cells in laboratory studies, and increases body weight in mice (Hao et al. 2012). DES also enhances autoantibody production in mice (Yurino et al. 2004).
Rosiglitazone, also known as Avandia, is a drug used to treat type 2 diabetes. It works by binding to PPAR receptors in fat cells and making the cells less insulin resistant. It also causes weight gain (and possibly heart attacks, and thus has been taken off the market in many countries). Activating PPAR receptors causes weight gain because these receptors play an important role in the development of fat cells and fat storage.
The interesting part is that some "obesogenic" environmental chemicals also bind to PPAR receptors, and therefore may also cause weight gain. Tributyltin, for example, binds the PPARγ receptor, and promotes fat cell development (Heindel et al. 2017). Phthalates also activate PPARγ receptors, and are linked to type 2 diabetes and insulin resistance (e.g., Lind et al. 2012; see more studies on the phthalates page).
There is animal evidence that the continuous use of birth control pills (i.e., not taking the "dummy" pills to avoid getting your period) can lead to insulin resistance, in mice anyway (Roso de Oliveira et al. 2019).
Statins-- drugs used for many people with diabetes to reduce the risk of cardiovascular disease-- may have side effects that affect the pancreas and the risk of diabetes. Numerous studies have found that statins are associated with an increased risk of type 2 diabetes (Chen et al. 2013; Dormuth et al. 2014; Jeong et al. 2019; Jones et al. 2017; Park et al. 2014; Preiss et al. 2011; Rajpathak et al. 2009; Sattar et al. 2010; Zigmont et al. 2019). Animal studies suggest that statins can decrease insulin secretion. One laboratory study, for example, has found that atorvastatin affected the mitochondria of rat pancreas cells (Sadighara et al. 2017).
Children who had obesity by age 3-5 years were more likely to have elevated levels of acetaminophen metabolites at birth (Sorrow et al 2018). In Denmark, prenatal exposure to acetaminophen was associated with overweight in girls at age 11 if exposure occurred in all 3 trimesters, and not with weight in boys (Liew et al. 2019).
The use of topical steroids, skin creams used to treat inflammatory skin conditions such as eczema and psoriasis, are associated with an increased risk of type 2 diabetes, according to a very large study from Denmark and the UK (Andersen et al. 2019).
In Japan, long-term antidepressant use increased the risk of type 2 diabetes. Glucose tolerance improved when antidepressants were discontinued or when the dose was reduced after diabetes onset (Miidera et al. 2020).
Thiazide diuretics have been linked to type 2 diabetes (Scheen 2018). Interestingly however, a randomized clinical trial of people with type 2 diabetes found that thiazide diuretics and SLGT2 inhibitors are effective into the removal of phthalates from the body (Mengozzi et al. 2020).
Prostate Cancer Drugs
Breast Cancer Drugs
Neonatal treatment with the pharmaceutical tamoxifen caused female mice to have increased fat mass, increased food intake, decreased physical activity and decreased energy expenditure, impaired glucose and insulin tolerance, and high fasting insulin and glucose levels. In contrast, exposed male mice had slightly improved glucose and insulin tolerance, and long-term decreased lean mass and decreased bone weight (Estrada-Meza et al. 2021).
Phosphatidylinositol 3-kinase (PI3K) inhibitors
Phosphoinositide_3-kinase_inhibitors are also cancer drugs, used to treat cancer such as lymphoma. Many are in trials now. One (small) study found that over half of the people taking them for cancer developed diabetes-- and almost a third of those people had remission of diabetes after stopping the drugs (Kim et al. 2019). For more on these drugs also see Hopkins et al. 2018 with commentaries from Greenhill 2018 and Harjes 2018.
Up to 50% of people who get an organ transplant and take immunosuppressants develop "Post Transplant Diabetes Mellitus." Metformin may help counteract this (Bhat et al. 2019).
Proton Pump Inhibitors
Regular use of proton pump inhibitors (PPIs), which are used to reduce stomach acid secretion, was associated with a higher risk of type 2 diabetes and the risk increased with longer duration of use (Yuan et al. 2020).
Transgender Hormone Therapy
Transitioning gender is associated with changes in insulin resistance. In transgender people, insulin sensitivity tends to increase with masculinization and to decrease with feminization (Shadid et al. 2019).
Antibiotics, Surgery, Radiation, and Other Medical Procedures
Studies on antibiotics and diabetes/obesity are discussed on the Diet and the Gut page, as are studies on bariatric surgery. Studies on radiation for cancer are discussed on the Radiation page. Other drugs linked to type 2 diabetes include steroids like prednisone (e.g., after kidney transplantation (Zbiti et al. 2012; Ponticelli et al. 2021), which also raise blood glucose levels in people with type 1 diabetes (Bevier et al. 2008). Growth hormones also can increase the risk of diabetes, although the good news is that children given growth hormones for short stature did not have an increased risk of diabetes at age 30 (Poidvin et al. 2017).
Acute pancreatitis in childhood is linked to an increased risk of type 2 diabetes in young adulthood (and not type 1 diabetes) (Bendor et al. 2019).
And totally unrelated but I think it is interesting, did you know that insulin-producing tumors are a thing? And that they can cause low blood sugar? Even in people with type 1 diabetes! (Gjelberg et al. 2017).
Like environmental chemicals, exposure to pharmaceuticals during development may contribute to diabetes or obesity-related effects in multiple subsequent generations. For example, the antibotic sulfomethoxazole is obesogenic in roundworms, and induces changes in gene expression linked to metabolism in multiple generations, even after exposure ends (Li et al. 2019).
Some studies have found that pregnant women taking certain anti-psychotic medications have an increased risk of gestational diabetes (Galbally et al. 2019; Kucukgoncu et al. 2019), while others have not (Wang et al. 2020). A systematic review and meta-analysis of the evidence from 10 studies concludes that the use of antipsychotic medications during pregnancy is associated with an increased risk of gestational diabetes in mothers, but that the evidence is still insufficient for specific drug classes (Wang et al. 2020).
Metformin and Pharmaceuticals in Wastewater
The diabetes medication metformin is a common pollutant released from wastewater treatment plants, and can act as an endocrine disruptor to fish and other organisms living in the water (Ambrosio-Albuquerque et al. 2021; Briones et al. 2016; Crago et al. 2016; Cummings et al. 2018; Elizalde-Velázquez and Gómez-Oliván 2019; Lee et al. 2018; Niemuth et al. 2015; Niemuth and Klaper 2018; Niemuth and Klaper 2015), and can affect the behavior of fish (MacLaren et al. 2018) and other species (Godoy et al. 2018).
Pharmaceuticals released from wastewater treatment plants are becoming more and more of a problem. Wastewater discharged from water treatment plants contains numerous endocrine disrupting compounds, and mice who drank this water gained more fat (Biasiotto et al. 2016). Chronic exposure to a mixture of pharmaceuticals and personal care products at levels found in the environment can induce developmental effects and metabolic dysfunction in both male and female fish, including changes in the gut (Hamid et al. 2021).
In China, metformin in wastewater is used as a method of tracking diabetes prevalence trends, and it tracks the trends quite well, as compared to more traditional methods (Xiao et al. 2019).
In people, however, metformin is not only an effective diabetes medication, it can also protect the beta cells and liver cells from the toxic effects of both arsenic and the food fatty acid butyric acid (Ahangarpour et al. 2017). It can protect against arsenic-induced cardiovascular problems in rats (Wang et al. 2019). Metformin may also be protective against the effects of air pollution in people with diabetes (Sade et al. 2015). The chemical PFOS (see the PFAS page) interferes with the glucose lowering effects of metformin in liver cells and made metformin less effective in fat cells (Salter et al. 2021).
Yet metformin taken during pregnancy is associated with an increased risk of offspring having a lower birthweight, and then later on a higher weight or being overweight in childhood (Hanem et al. 2019; Hanem et al. 2018; Rowan et al. 2018; reviewed by Tarry-Adkins et al. 2019; Xu et al. 2019). Although some studies have not found this to be the case (Paavilainen et al. 2021). Metformin during pregnancy may not affect offspring cognitive function on average, although this issue deserves more study (Greger et al. 2020). A review discusses the pros and cons of taking metformin while pregnant (Jorquera et al. 2020).
Sterilizing wastewater with sodium hypochlorite can react with pharmaceuticals to generate disinfection by-products and can cause the final effluent to be even more harmful to aquatic organisms. One study, for example, found that the metabolism of Daphnia magna is sensitive to changes in the final effluent that are caused by sterilization. With the addition of the persistent contaminant PFOS, the metabolic profile is further altered (Wagner et al. 2019). Another study found that chlorination combined with metformin is toxic to worms and to human intestinal cells, and harmful to mice and the mouse small intestine (Zhang et al. 2020).