Two medicines, side by side
Metformin vs pioglitazone
Metformin and pioglitazone are both labeled for type 2 diabetes. Drugs@FDA records approvals of metformin since 1995 and of pioglitazone since 1999. Pharmacies paid $0.0145 per metformin HCl 500 mg tablet and $0.0675 per pioglitazone HCl 15 mg tablet (NADAC, October 7, 2026); the strengths differ, so the two prices are not like for like. In FDA's classes, metformin is a biguanide and pioglitazone a peroxisome proliferator receptor gamma agonist.
Check it at the source: the metformin FDA label on DailyMed (effective September 3, 2026); the pioglitazone FDA label on DailyMed (effective March 28, 2025).
Highlights of the metformin record
Metformin (Glucophage) · label of September 3, 2026
WARNING: LACTIC ACIDOSIS Postmarketing cases of metformin-associated lactic acidosis have resulted in death, hypothermia, hypotension, and resistant bradyarrhythmias. The onset of metformin-associated lactic acidosis is often subtle, accompanied only by nonspecific symptoms such as malaise, myalgias, respiratory distress, somnolence, and abdominal pain.
Used for
From the label: indicationsMetformin hydrochloride extended-release tablets are indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. Metformin hydrochloride extended-release tablets are biguanide indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus
On the market
- Earliest approval on file
- March 3, 1995
- Generic labelers
- 80 labelers
- Pharmacy cost
- $0.0145 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 61
Highlights of the pioglitazone record
Pioglitazone (Actos) · label of March 28, 2025
CONGESTIVE HEART FAILURE
Thiazolidinediones, including ACTOS ® , cause or exacerbate congestive heart failure in some patients [see Warnings and Precautions (5.1) ].
After initiation of ACTOS, and after dose increases, monitor patients carefully for signs and symptoms of heart failure (e.g., excessive, rapid weight gain, dyspnea, and/or edema).
Used for
From the label: indicationsMonotherapy and Combination Therapy ACTOS is indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus in multiple clinical settings [see Clinical Studies (14) ]. Important Limitations of Use ACTOS exerts its antihyperglycemic effect only in the presence of endogenous insulin. […]
On the market
- Earliest approval on file
- July 15, 1999
- Generic labelers
- 22 labelers
- Pharmacy cost
- $0.0675 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 2
Source: FDA drug labels via openFDA (Metformin label of September 3, 2026, Pioglitazone label of March 28, 2025); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do metformin and pioglitazone differ on the record?
In FDA's classes, metformin is a biguanide and pioglitazone a peroxisome proliferator receptor gamma agonist.
How each works, in its label's words: Metformin, “Metformin is a biguanide that improves glucose tolerance in patients with type 2 diabetes, lowering both basal and postprandial plasma glucose.”; Pioglitazone, “ACTOS is a thiazolidinedione that depends on the presence of insulin for its mechanism of action.”
Half-life, in each label's words: Metformin, “Following oral administration, approximately 90% of the absorbed drug is eliminated via the renal route within the …”; Pioglitazone, “The mean serum half-life (t 1/2 ) of pioglitazone and its metabolites (M-III and M-IV) range from three to seven hours …”
Both labels carry a boxed warning; the records quote them.
Generics: metformin since 2002; pioglitazone since 2012 (Drugs@FDA).
| Metformin | Pioglitazone | |
|---|---|---|
| Labeled for | Type 2 diabetes | Type 2 diabetes |
| Pharmacologic class | Biguanide | Peroxisome Proliferator Receptor alpha Agonist, Peroxisome Proliferator Receptor gamma Agonist, Thiazolidinedione |
| How it works (label) | Metformin is a biguanide that improves glucose tolerance in patients with type 2 diabetes, lowering both basal and postprandial plasma glucose. | ACTOS is a thiazolidinedione that depends on the presence of insulin for its mechanism of action. |
| Half-life (label) | Following oral administration, approximately 90% of the absorbed drug is eliminated via the renal route within the first 24 hours, with a plasma elimination half-life of approximately 6.2 hours. | The mean serum half-life (t 1/2 ) of pioglitazone and its metabolites (M-III and M-IV) range from three to seven hours and 16 to 24 hours, respectively. |
| Earliest approval on file (Drugs@FDA) | March 3, 1995 | July 15, 1999 |
| First generic approved | January 24, 2002 | August 17, 2012 |
| Generic labelers (NDC) | 80 labelers | 22 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.0145 per tablet (Metformin HCl 500 mg tablet) | $0.0675 per tablet (Pioglitazone HCl 15 mg tablet) |
| 12-month price change | -1% | -7% |
| Boxed warning | Yes | Yes |
| Shortage now | No current entry | No current entry |
| Recalls recorded | 61 | 2 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 410,076 | 44,186 |
| DEA schedule | none | none |
Source: Drugs@FDA, FDA NDC Directory, CMS NADAC of October 7, 2026, FDA shortages and recalls, FAERS via openFDA (FDA files October 8, 2026)
What next?
- Alternatives to metformin
- every medicine labeled for the same conditions