Lantus Manufacturing, Supply & Shortage History: What Women With Diabetes Need to Know

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What Is Lantus and How Does It Work?

Lantus delivers a steady, nearly peakless background insulin over roughly 20 to 24 hours. It covers your baseline glucose needs between meals and overnight, without the sharp action-curve spikes of short-acting insulins. That flat profile is the whole point: one injection per day keeps fasting glucose from climbing while you sleep.

The biochemistry behind the flat curve

Insulin glargine differs from human insulin at two points on its amino acid chain. An asparagine at position A21 is replaced with glycine, and two arginine residues are added to the B-chain C-terminus. Those changes shift the molecule's isoelectric point toward physiologic pH, meaning the solution precipitates into microcrystals in subcutaneous tissue after injection. Absorption from those microcrystals is slow and sustained, producing a duration of action of 20 to 24 hours in most adults.

Once absorbed, insulin glargine is metabolized into two active metabolites (M1 and M2) that bind the insulin receptor with affinity similar to human insulin. M1 is the predominant circulating metabolite in people with type 1 or type 2 diabetes and is responsible for most of the glucose-lowering effect.

How this differs from NPH and other basal insulins

NPH insulin peaks at 4 to 8 hours and lasts only 10 to 18 hours, so many women needed two injections per day. Detemir (Levemir) has a similar flat profile to glargine but shorter duration (up to 18 to 20 hours) in some patients, which can also require twice-daily dosing. In the FLAIR trial, insulin degludec (Tresiba) showed fewer nocturnal hypoglycemia episodes compared with glargine U-100, though both are approved for once-daily use. Glargine U-300 (Toujeo) delivers the same molecule at three times the concentration, extending action slightly further and reducing injection volume.

How Lantus Is Manufactured

Sanofi produces insulin glargine using recombinant DNA technology in a non-pathogenic laboratory strain of Escherichia coli (K12). The process is a multi-stage biologics pipeline, not a simple chemical synthesis.

The recombinant DNA production process

The gene encoding the modified insulin glargine precursor is inserted into E. Coli expression systems. Bacteria are grown in large-scale fermentation tanks, then lysed to recover inclusion bodies containing the precursor protein. Those inclusion bodies are solubilized, refolded, and enzymatically processed to cleave the precursor into the two-chain insulin structure. Purification involves multiple chromatography steps to remove host-cell proteins, endotoxins, and process-related impurities.

The final bulk drug substance is formulated at pH 4.0 with zinc, m-cresol as a preservative, and glycerol. That acidic formulation is what keeps glargine in solution in the vial; once injected into the neutral pH of subcutaneous tissue, precipitation begins.

Fill-finish and device manufacturing

Sanofi manufactures Lantus at facilities in Frankfurt, Germany (bulk biologics) and at secondary sites for fill-finish operations. The SoloStar prefilled pen, which accounts for the majority of Lantus prescriptions in the U.S., involves separate device manufacturing and assembly. Regulatory filings with the FDA require site-specific approval for each manufacturing location, which is one reason why rapidly shifting production during a shortage is not straightforward.

The regulatory pathway that opened the door to biosimilars

Because insulin glargine is a biological product (not a small-molecule drug), the pathway for copies is the FDA 351(k) biosimilar pathway rather than an ANDA. Biosimilar applicants must demonstrate no clinically meaningful differences in safety, purity, and potency. Three products have cleared that bar:

• Basaglar (Eli Lilly/Boehringer Ingelheim): approved December 2015, launched in the U.S. December 2016
• Semglee (Mylan/Viatris): approved July 2021 as the first interchangeable biosimilar insulin in U.S. History
• Rezvoglar (Eli Lilly): approved December 2022

Semglee's interchangeable designation means pharmacists in most states can substitute it for Lantus without a new prescription, which is clinically meaningful if you arrive at a pharmacy that is out of branded product.

Lantus Supply and Shortage History

Insulin access is a genuine public health problem in the United States. A 2021 analysis in JAMA Internal Medicine found that insulin prices in the U.S. Were roughly ten times higher than in comparable high-income countries, which creates a functional shortage even when physical supply is stable. Physical manufacturing shortages are a separate but overlapping problem.

The 2017 to 2019 insulin price and access crisis

No formal FDA manufacturing shortage designation for Lantus occurred during this period, but access failures were widespread. Studies documented that one in four Americans with insulin-requiring diabetes was rationing doses because of cost. Rationing included skipping injections, reducing doses, and delaying refills, all of which produce preventable hyperglycemia and diabetic ketoacidosis admissions. Women with type 1 diabetes and lower incomes were disproportionately affected, a pattern documented in surveys by the T1D Exchange.

Sanofi responded by capping out-of-pocket costs through its Insulins Valyou Savings Program, but program eligibility and awareness were inconsistent.

The 2021 to 2023 demand pressure period

The explosion of GLP-1 receptor agonist prescriptions for weight management, combined with pandemic-era supply chain disruptions, placed unusual strain on several diabetes drug supply chains. While semaglutide (Ozempic, Wegovy) and tirzepatide (Mounjaro, Zepbound) carried formal FDA shortage designations, basal insulin supply was secondarily affected through distribution channel strain.

The FDA drug shortage database did not list Lantus as a nationally short product during this window, but anecdotal pharmacy-level shortages were reported in rural areas and independent pharmacies with lower purchasing power. Sanofi's manufacturing scale at its Frankfurt biologics campus was not the rate-limiting factor; domestic distribution and pharmacy-level stocking decisions were.

Current status (early 2025)

The FDA drug shortage database does not list Lantus (insulin glargine U-100) as currently in shortage at the national level. Semglee is available as a lower-cost interchangeable option at most major pharmacy chains. Sanofi launched Lilly's Insulin Value Program is separate; Sanofi's own Valyou program offers Lantus at $99 per month for eligible cash-pay patients.

The WomanRx Insulin Access Framework: if your pharmacy reports Lantus is unavailable, work through this sequence with your clinician or telehealth provider:

1. Ask the pharmacist to check Semglee (interchangeable biosimilar; may be swapped without a new script in most states).
2. If Semglee is also unavailable, Basaglar or Rezvoglar require a new prescription but are therapeutically equivalent.
3. If all glargine products are unavailable, insulin detemir (Levemir) is the next closest in duration and profile; dose conversion is approximately 1:1 but individual titration is needed.
4. Do not switch to NPH without clinician guidance; the twice-daily dosing and peak action require dose restructuring.

Lantus Across Women's Life Stages

Reproductive years and PCOS

Women with polycystic ovary syndrome carry approximately a four-fold higher risk of type 2 diabetes compared with women without PCOS, even after controlling for BMI. Insulin resistance is the core metabolic defect in most PCOS phenotypes. If metformin and lifestyle changes fail to maintain glycemic targets, basal insulin is sometimes added.

The menstrual cycle itself affects insulin sensitivity. Progesterone rises in the luteal phase and reduces peripheral insulin sensitivity, meaning your insulin requirements may rise in the 7 to 10 days before your period and drop again after bleeding begins. Women with type 1 diabetes tracking this pattern often need to increase their basal insulin dose by 5 to 20 percent in the luteal phase. Continuous glucose monitoring data from the CONCEPTT trial in women with type 1 diabetes illustrate how tightly glucose management needs to shift across reproductive milestones.

Perimenopause and menopause

Estrogen has direct insulin-sensitizing effects. As ovarian estrogen production declines in perimenopause, insulin resistance frequently worsens, increasing the risk of type 2 diabetes by an estimated 4 to 6 percent per year of menopausal transition. Women already on basal insulin may find their doses creeping up in their late 40s without any change in diet or exercise.

Sleep disruption, the most common perimenopausal symptom, further degrades insulin sensitivity independent of hormonal changes. Hot flashes overnight disrupt restorative sleep, raise cortisol, and push fasting glucose higher. If you are titrating Lantus during perimenopause and your fasting numbers are unexpectedly high despite consistent dosing, poor sleep quality is worth addressing in parallel.

Postmenopausal women on menopausal hormone therapy (MHT) with estradiol show improved insulin sensitivity and lower fasting glucose compared with untreated postmenopausal women in the KEEPS trial. That means your basal insulin dose may actually need to decrease if you start MHT. Monitor closely in the first 4 to 8 weeks.

Pregnancy and Lactation Safety

Insulin glargine is the preferred long-acting insulin in pregnancy for many clinicians, though the evidence base has specific nuances worth understanding.

Pregnancy safety data

The FDA originally assigned Lantus to Pregnancy Category C (risk cannot be ruled out) under the old lettering system. Under the current Pregnancy and Lactation Labeling Rule (PLLR), the label states that available data from published studies and postmarketing surveillance do not demonstrate a drug-associated risk of major birth defects or miscarriage. ACOG Practice Bulletin 201 supports the use of insulin glargine in pregestational diabetes when glycemic targets are difficult to achieve with human insulins alone.

The largest prospective comparative study was the GLAT (Glargine and NPH in Pregnancy) registry, which found no significant difference in congenital malformation rates between glargine-exposed and NPH-exposed pregnancies. A 2018 meta-analysis covering over 700 pregnancies similarly found no elevated teratogenic signal.

Placental transfer of insulin glargine is minimal. Because insulin is a large protein molecule, it does not cross the placenta in clinically significant amounts at therapeutic doses. The fetus is not exposed to exogenous insulin from your injections.

Maintaining tight glycemic control in pregnancy is far more important to fetal outcomes than which basal insulin you use. The HAPO study demonstrated a continuous relationship between maternal glucose and adverse perinatal outcomes including macrosomia, neonatal hypoglycemia, and cesarean delivery.

Gestational diabetes

Insulin is the first-line pharmacologic treatment for gestational diabetes (GDM) when nutritional therapy fails to achieve targets. ACOG Practice Bulletin 190 recommends insulin as the preferred agent. NPH and regular insulin have the longest track records in GDM, but glargine is used off-label with an acceptable safety profile when once-daily dosing improves adherence.

Lactation

The manufacturer's label notes that it is not known whether insulin glargine is excreted in human milk. Insulin is a large peptide and is not expected to be absorbed through the infant's gastrointestinal tract in meaningful amounts even if present in breast milk. No adverse effects in breastfed infants have been reported in published case series.

Women who are breastfeeding often have lower insulin requirements than pre-pregnancy because lactation itself is metabolically demanding and improves insulin sensitivity. Expect to reduce your basal dose gradually after delivery and during the breastfeeding period, and monitor fasting glucose more frequently in the first 6 to 8 weeks postpartum.

Contraception note

Insulin glargine is not a teratogen with a mandated contraception requirement the way some agents (like valproate or isotretinoin) are. However, unplanned pregnancy in a woman with poorly controlled diabetes carries substantial risks including a 3 to 5 times higher rate of major congenital anomalies compared with the general population. Pre-conception counseling and achieving an HbA1c below 6.5 percent before conception reduces that risk substantially. If you are using Lantus and are not actively trying to conceive, effective contraception remains clinically advisable.

Who Lantus Is Right For and Who Should Consider Alternatives

Women who may do well on Lantus

• Type 1 or type 2 diabetes requiring basal insulin with once-daily dosing
• Women who have been stable on Lantus and have no access or cost barrier
• Pregnant women with pregestational diabetes when glargine is preferred by their obstetric team
• Women with PCOS-related type 2 diabetes who have progressed beyond oral agents
• Postmenopausal women with type 2 diabetes needing reliable overnight coverage

Women who may need a different approach

• Women who need more flexible dosing: insulin degludec (Tresiba) offers a longer, more forgiving duration and lower nocturnal hypoglycemia rates in the SWITCH 2 trial
• Women with cost barriers: Semglee (interchangeable biosimilar) is priced lower at most pharmacies; the over-the-counter ReliOn brand NPH/regular at Walmart is an emergency fallback but requires dose restructuring
• Women who cannot tolerate the injection volume of U-100 at higher doses: Toujeo (glargine U-300) delivers the same total dose in one-third the volume
• Women considering GLP-1 therapy: for type 2 diabetes, the combination of a GLP-1 receptor agonist with basal insulin is supported by data from the LixiLan-O trial, and some women can eventually reduce or discontinue basal insulin if GLP-1 therapy achieves sufficient glycemic control

The ORIGIN Trial: What It Means for Women

The ORIGIN trial (NEJM 2012) enrolled 12,537 adults with dysglycemia (impaired fasting glucose, impaired glucose tolerance, or early type 2 diabetes) and randomized them to insulin glargine or standard care. The median follow-up was 6.2 years.

The primary finding: insulin glargine did not increase or decrease the rate of cardiovascular events. The hazard ratio for the primary outcome (death from cardiovascular causes, nonfatal MI, or nonfatal stroke) was 1.02 (95% CI, 0.94 to 1.11). Cancer rates were also similar between groups.

Women were underrepresented in ORIGIN. The trial enrolled roughly 35 percent women, and sex-stratified cardiovascular outcomes were not published as a primary analysis. This is the evidence gap that WomanRx flags explicitly: we do not have powered, sex-stratified cardiovascular safety data for insulin glargine in early dysglycemia. What we can say is that the ORIGIN neutral result is likely applicable to women with similar baseline risk, but the female-specific cardiovascular physiology (women present with atypical MI symptoms, have different coronary microvascular disease patterns, and respond differently to some antidiabetic agents) was not the focus of the trial design.

ORIGIN did confirm one point that matters for women with PCOS or prediabetes considering early insulin: glargine did not accelerate weight gain more than standard care in the dysglycemia population, with a median weight difference of only 1.6 kg at 6.2 years.

Comparing Lantus to Its Biosimilars and Competitors

| Product | Manufacturer | Interchangeable with Lantus? | Concentration | Notable difference | |---|---|---|---|---| | Lantus | Sanofi | Reference product | U-100 | Longest clinical track record | | Basaglar | Eli Lilly | No (biosimilar, not interchangeable) | U-100 | SoloStar-style KwikPen | | Semglee | Mylan/Viatris | Yes (FDA-designated) | U-100 | First interchangeable biosimilar insulin | | Rezvoglar | Eli Lilly | No (biosimilar) | U-100 | Tempo Pen device | | Toujeo | Sanofi | No (different concentration) | U-300 | Smaller volume, possibly longer action | | Tresiba | Novo Nordisk | No (different molecule: degludec) | U-100/U-200 | Lower nocturnal hypoglycemia vs glargine |

Switching between any of these products requires a clinician conversation. Dose is not always 1:1 across concentrations (especially moving from U-100 to U-300) and individual titration is always required.

Practical Steps If Your Pharmacy Is Out of Lantus

Your pharmacist is your first-line resource, not a barrier. Here is a concrete sequence:

1. Ask the pharmacist whether Semglee is in stock. Because it is FDA-designated interchangeable, they may substitute it without contacting your prescriber in many states.
2. If Semglee is unavailable, ask your prescriber (or WomanRx clinician) to send a new prescription for Basaglar or Rezvoglar, using the same unit dose.
3. If you need a bridge while waiting for a prescription, contact Sanofi's Insulins Valyou program (1-888-847-4877) for emergency supply options.
4. Never halve your basal insulin dose to stretch supply without clinician guidance. Halving your dose risks severe hyperglycemia and, in type 1 diabetes, diabetic ketoacidosis within hours.
5. If you are pregnant and your basal insulin is unavailable, go directly to your obstetric team or an emergency department rather than rationing.

A 2022 report from the Health Care Cost Institute found that diabetes-related emergency department visits remain disproportionately high among women aged 18 to 44, the reproductive-age group most likely to be managing type 1 diabetes. Supply chain disruptions that produce even brief gaps in insulin availability translate directly into preventable hospitalizations for this group.