Two medicines, side by side
Metformin vs sitagliptin
Metformin and sitagliptin are both labeled for type 2 diabetes. Drugs@FDA records approvals of metformin since 1995 and of sitagliptin since 2006. Pharmacies paid $0.0145 per metformin HCl 500 mg tablet and $3.77 per sitagliptin phosphate 100 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 sitagliptin a dipeptidyl peptidase 4 inhibitor.
Check it at the source: the metformin FDA label on DailyMed (effective September 3, 2026); the sitagliptin FDA label on DailyMed (effective November 14, 2024).
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 sitagliptin record
Sitagliptin (Januvia) · label of November 14, 2024
Used for
From the label: indicationsJANUVIA ® is indicated as an adjunct to diet and exercise to improve glycemic control in adults with type 2 diabetes mellitus. JANUVIA is a dipeptidyl peptidase-4 (DPP-4) inhibitor 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
- October 16, 2006
- Generic labelers
- 4 labelers
- Pharmacy cost
- $3.77 per tablet
Supply and safety
- Shortage
- No current entry
- Recalls
- 1
Source: FDA drug labels via openFDA (Metformin label of September 3, 2026, Sitagliptin label of November 14, 2024); NDC Directory, Drugs@FDA, NADAC, FDA shortages and recalls (October 8, 2026)
How do metformin and sitagliptin differ on the record?
In FDA's classes, metformin is a biguanide and sitagliptin a dipeptidyl peptidase 4 inhibitor.
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.”; Sitagliptin, “Sitagliptin is a DPP-4 inhibitor, which is believed to exert its actions in patients with type 2 diabetes mellitus by slowing the inactivation of incretin hormones.”
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 …”; Sitagliptin, “Following a single oral 100-mg dose to healthy volunteers, mean plasma AUC of sitagliptin was 8.52 μM•hr, C max was 950 …”
Only the metformin label carries a boxed warning.
Generics: metformin since 2002; sitagliptin since 2025 (Drugs@FDA).
| Metformin | Sitagliptin | |
|---|---|---|
| Labeled for | Type 2 diabetes | Type 2 diabetes |
| Pharmacologic class | Biguanide | Dipeptidyl Peptidase 4 Inhibitor |
| 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. | Sitagliptin is a DPP-4 inhibitor, which is believed to exert its actions in patients with type 2 diabetes mellitus by slowing the inactivation of incretin hormones. |
| 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. | Following a single oral 100-mg dose to healthy volunteers, mean plasma AUC of sitagliptin was 8.52 μM•hr, C max was 950 nM, and apparent terminal half-life (t 1/2 ) was 12.4 hours. |
| Earliest approval on file (Drugs@FDA) | March 3, 1995 | October 16, 2006 |
| First generic approved | January 24, 2002 | December 29, 2025 |
| Generic labelers (NDC) | 80 labelers | 4 labelers |
| Pharmacy cost (NADAC, each one's most listed form; strengths differ) | $0.0145 per tablet (Metformin HCl 500 mg tablet) | $3.77 per tablet (Sitagliptin phosphate 100 mg tablet) |
| 12-month price change | -1% | n/a |
| Boxed warning | Yes | No |
| Shortage now | No current entry | No current entry |
| Recalls recorded | 61 | 1 |
| FAERS reports (a report is not proof of cause; counts follow how widely a medicine is used) | 410,076 | 74,197 |
| 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