Retatrutide not detected in urine, reports show weight loss and DKA

These three reports sit at different edges of the evidence: whether the drug can be found in urine, a rare genetic obesity syndrome, and off-label use in type 1 diabetes ¹.

The detection study started with four people who gave themselves retatrutide at 2 mg under the skin on days 1 and 7 ¹. The investigators built a lab technique called liquid chromatography-high resolution mass spectrometry (LC-HRMS), which separates and identifies molecules, and they validated it to anti-doping standards for selectivity, reliability, robustness, and stability ¹. They looked for a specific charged form of the drug, the [M+3H]3+ precursor ion, and confirmed it with a second check that watches fragment ions ¹. The smallest amount the test could reliably detect was 6.14 ng/mL in blood plasma and 2.44 ng/mL in urine ¹. Despite trying several ways to prepare the samples, the researchers did not find intact retatrutide or breakdown products in urine at any collection point ¹. The abstract did not fully report how drug levels in blood changed over time, but the negative urine finding is direct and specific to this method and this four-person sample ¹. This does not prove retatrutide never appears in urine. It shows that, under this protocol, urine was not a reliable sample for detecting the drug ¹. For anti-doping programs, the practical point is that plasma may be needed to monitor retatrutide use until more excretion data are available ¹.

The Prader-Willi case involved a 29-year-old man with a genetically confirmed condition called maternal uniparental disomy, a body mass index (BMI) of 59.7 kg/m2, and newly diagnosed type 2 diabetes with an HbA1c of 8.3%, a measure of average blood sugar over about three months ². He received a series of medicines that act on incretin hormones, the gut signals involved in appetite and blood sugar ². The sequence was retatrutide at 1 to 12 mg weekly inside a clinical trial, then oral semaglutide, and then dulaglutide after retatrutide became unavailable, along with a structured reduced-calorie diet and supervised exercise ². At 18 months, total weight loss was 58.8%, equal to 108.7 kg lost, and HbA1c was 4.9% with all glucose-lowering medicines stopped ². Mild, temporary stomach and gut symptoms occurred during dose increases, and no serious adverse events were reported ². A later body composition scan called bioimpedance showed skeletal muscle mass of 38.5 kg after that 58.8% weight loss ². This single case shows large weight loss in a syndrome where durable loss is rarely achieved, but the sequential treatment and structured lifestyle make it impossible to say the outcome came from retatrutide or any one medicine alone ².

The third report describes a 20-year-old woman with type 1 diabetes who used insulin as a long-acting background dose plus mealtime doses, called basal-bolus insulin, and who started retatrutide to lose weight ³. She had bought the drug from a friend who purchased it in the United States, and she reported taking three doses, with the last dose the day before she arrived at the hospital ³. She came in with severe vomiting that would not stop, a fast heart rate but stable circulation, and severe diabetic ketoacidosis. Her blood glucose was 20 mmol/L, ketones were 6.4 mmol/L, blood acidity was pH 6.8, and bicarbonate was 4 mmol/L ³. She was treated with a steady insulin drip and fluids through a vein ³. The abstract states that retatrutide's safety profile in people with type 1 diabetes has not yet been established ³. This case does not prove cause and effect, but it places a serious metabolic event in the small, off-label evidence base for retatrutide in type 1 diabetes ³. People with type 1 diabetes were not included in the phase 2 obesity or diabetes trials used to show what retatrutide can do, so this population remains outside the controlled evidence ³.

Existing controlled trials show a different picture. In a phase 3 type 2 diabetes trial called TRANSCEND-T2D-1, retatrutide reduced HbA1c by up to 1.94% and body weight by up to 15.3% over 40 weeks, with stomach and gut side effects that were generally manageable ⁴. In a phase 2 obesity trial, the highest retatrutide dose produced 24.2% weight loss at 48 weeks ⁵. In a 24-week trial for metabolic dysfunction-associated steatotic liver disease (MASLD), a form of fatty liver disease, liver fat decreased by 42.9% to 82.4% depending on dose, and 86% of participants on 8 to 12 mg reached normal liver fat ⁶. The new case reports do not conflict with those efficacy findings. The Prader-Willi case extends the observation of large weight loss to a rare syndrome marked by extreme hunger, but it cannot be compared directly because treatment was sequential and included semaglutide, dulaglutide, diet, and exercise ². The type 1 diabetes case sits outside the controlled trial populations and suggests off-label use may carry risks not captured in type 2 diabetes or obesity studies ³. These case reports do not compare retatrutide with approved medicines in the same broader gut-hormone class, such as liraglutide, or with investigational combinations such as cagrilintide.

First, the urine detection study has only four users and a single dose schedule of 2 mg on days 1 and 7. Other doses, longer collection periods, or different sample preparation methods may produce a different result ¹. Second, the Prader-Willi case cannot tell us what retatrutide alone would achieve, because the patient moved through three different medicines and also followed a structured diet and exercise program ². Third, the type 1 diabetes case is a single adverse event without a control group, and the contribution of retatrutide compared with reduced food intake, vomiting, or not enough insulin cannot be separated ³. Finally, longer-term kidney and cardiovascular outcomes are still being studied in the kidney outcome program called TRANSCEND-CKD and the TRIUMPH registrational program for obesity, obstructive sleep apnea, and knee osteoarthritis, so the full safety margin for retatrutide is not yet established ⁷. The evidence does not establish that retatrutide is safe or effective in type 1 diabetes, that urine will consistently be negative, or that a single medicine can produce the Prader-Willi outcome ¹.