SGLT2 Inhibitors

What it is

SGLT2 inhibitors are oral drugs that lower blood glucose by blocking kidney glucose reabsorption and are usually taken once daily. Also called sodium-glucose co-transporter 2 inhibitors or gliflozins, this class includes canagliflozin, dapagliflozin, empagliflozin, ertugliflozin, and in some markets bexagliflozin. Their importance now goes beyond diabetes: several agents also reduce hospitalization for heart failure and slow progression of chronic kidney disease, including in some people without diabetes.

These medicines were first introduced for type 2 diabetes, but large clinical trials changed practice by showing heart and kidney benefits that are not explained by glucose lowering alone. In routine care, they are often considered when a person with type 2 diabetes also has atherosclerotic cardiovascular disease, heart failure, or chronic kidney disease. In India, where type 2 diabetes and diabetic kidney disease are common, this class is increasingly relevant, but access, cost, dehydration risk in hot weather, and genital infection counseling matter in real-world use.

Common drugs in the class:

Drug	Common use areas
Canagliflozin	Type 2 diabetes, kidney and cardiovascular risk reduction in selected patients
Dapagliflozin	Type 2 diabetes, heart failure, chronic kidney disease
Empagliflozin	Type 2 diabetes, heart failure, cardiovascular and kidney benefit
Ertugliflozin	Type 2 diabetes
Bexagliflozin	Type 2 diabetes in some markets

How it works

SGLT2 is a transport protein in the proximal tubule of the kidney. Under normal conditions, it reabsorbs much of the filtered glucose back into the bloodstream. SGLT2 inhibitors block this transporter, so more glucose is lost in urine. This lowers blood glucose without directly increasing insulin secretion.

Because they cause glucose and sodium loss in urine, these drugs can also lead to:

1. Mild osmotic diuresis and natriuresis, which may lower blood pressure.
2. Modest weight loss, partly from calorie loss in urine.
3. Reduced intraglomerular pressure in the kidney, which is one reason they may protect kidney function.
4. Benefits in heart failure, likely through several mechanisms, including reduced congestion and favorable kidney-heart effects.

Their glucose-lowering effect depends on kidney filtration, so it may be less pronounced at lower estimated glomerular filtration rate (eGFR). Even so, kidney and heart benefits may still persist in people with chronic kidney disease, depending on the specific drug and indication.

Evidence and uses

SGLT2 inhibitors are established treatments for type 2 diabetes, especially when there is coexisting cardiovascular disease, heart failure, or chronic kidney disease. They lower HbA1c modestly compared with some other diabetes drugs, but their major value is that they can improve outcomes beyond glucose numbers.

Main evidence-based uses include:

Condition	What the class can do
Type 2 diabetes	Lowers blood glucose, with low intrinsic risk of hypoglycemia when used alone
Heart failure	Reduces hospitalization risk in HFrEF and HFpEF for selected patients
Chronic kidney disease	Slows kidney disease progression and lowers risk of kidney-related outcomes in selected patients
Cardiovascular risk in diabetes	Some agents reduce major cardiovascular events or cardiovascular death in high-risk groups

Important points about use:

• They are not first-line for every person with diabetes, but they are strongly favored in many people with heart or kidney disease.
• They are not a substitute for insulin in type 1 diabetes. In many settings, routine use in type 1 diabetes is avoided because of diabetic ketoacidosis risk.
• They can be used alone or with metformin, GLP-1 receptor agonists, insulin, or other glucose-lowering drugs.

The class effect is strong for heart failure and kidney protection, but not every drug has identical approvals or trial evidence. Clinicians choose among agents based on kidney function, approved indications, cost, and patient-specific risks.

Safety and interactions

SGLT2 inhibitors are generally well tolerated, but they have important adverse effects and counseling points.

Common or clinically important risks:

1. Genital fungal infections. These are among the most common side effects because urine contains more glucose. They are usually treatable, but recurrence can happen.
2. Urinary tract infections. Risk may be slightly increased in some patients, though severe infections are uncommon.
3. Volume depletion. Because these drugs increase urination, they can cause dizziness, low blood pressure, or dehydration, especially in older adults, people taking diuretics, or during hot weather, fasting, vomiting, or diarrhea.
4. Diabetic ketoacidosis (including euglycemic DKA). This is uncommon but serious. Blood glucose may be only mildly elevated, so symptoms such as nausea, vomiting, abdominal pain, rapid breathing, or unusual fatigue need urgent assessment.
5. Acute kidney function changes. A small early dip in eGFR can occur after starting therapy, but this is often hemodynamic rather than true injury. Persistent worsening needs review.
6. Rare severe genital infection such as Fournier gangrene has been reported.
7. Lower-limb amputation and fracture concerns were raised particularly with canagliflozin in earlier data, though risk interpretation has evolved and depends on patient factors.

Drug and care interactions:

• Combining with insulin or sulfonylureas can increase hypoglycemia risk because of the other drug, not because SGLT2 inhibitors alone usually cause hypoglycemia.
• Combining with diuretics can increase dehydration or low blood pressure risk.
• They are often held before major surgery and during acute serious illness to reduce ketoacidosis risk. Patients should follow clinician-specific sick-day instructions.

People taking these medicines should discuss genital hygiene, hydration, and when to pause the drug during illness. Do not start, stop, or restart an SGLT2 inhibitor without advice from a clinician or pharmacist who knows your kidney function and other medicines.

When to see a clinician

Seek medical advice promptly if you take an SGLT2 inhibitor and develop:

• Symptoms of ketoacidosis such as nausea, vomiting, abdominal pain, deep or rapid breathing, or marked weakness
• Fainting, severe dizziness, or signs of dehydration
• Burning urination, fever, flank pain, or recurrent genital infections
• New foot ulcers, severe leg pain, or signs of poor circulation
• Sudden drop in urine output or worsening swelling

Before starting treatment, clinicians usually review kidney function, blood pressure, current diabetes medicines, and infection history. Follow-up often includes renal function tests, glucose monitoring, and review of side effects.

Limitations and open questions

SGLT2 inhibitors have strong evidence for type 2 diabetes, heart failure, and chronic kidney disease, but they are not appropriate for everyone. Benefits and approvals differ by drug, kidney function threshold, and whether the person has diabetes, heart failure subtype, or albuminuric kidney disease.

Evidence in humans is still evolving for some newer uses, combinations, and lower-risk populations. Questions remain about the best sequencing with GLP-1 receptor agonists, how to individualize therapy in frail older adults, and how to improve safe use during fasting, acute illness, and perioperative care. In India and other hot climates, practical issues such as dehydration risk, affordability, and access to follow-up may affect who benefits most from this class.