A Phase 2 interventional study of Acetazolamide 62.5 mg and Acetazolamide 125 mg in T2D, sponsored by University Health Network, Toronto. Not yet recruiting at 1 site in Canada. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-10-29.
Sponsored by University Health Network, Toronto · Phase 2, Interventional, and Treatment
The study aims to determine the acute efficacy and safety of three sequential doses of acetazolamide (62.5 mg, 125 mg, 250 mg) each for 2 weeks in 20 patients with T2D receiving background SGLT2i therapy.
Chronic kidney disease (CKD) is a common complication of type 2 diabetes (T2D) and is associated with an increased risk of kidney failure, cardiovascular disease, and premature death. Although current standard-of-care therapies, including renin-angiotensin-aldosterone system inhibitors (RAASi), sodium-glucose cotransporter-2 inhibitors (SGLT2i), glucagon-like peptide-1 receptor agonists (GLP-1RA), and non-steroidal mineralocorticoid receptor antagonists (nsMRA), slow CKD progression, patients continue to experience substantial residual risk of kidney function decline despite treatment. Hyperfiltration remains a central driver of CKD progression and represents an important therapeutic target. Acetazolamide is a carbonic anhydrase inhibitor that has been used clinically for decades and has been shown to reduce glomerular hyperfiltration by increasing distal sodium delivery. Previous studies have demonstrated that acetazolamide produces an acute, reversible reduction in glomerular filtration rate (GFR), although its effects in patients with T2D receiving background SGLT2i therapy have not been evaluated. The Adding AcetazolamIde on top of SGLT2 inhibition in Persons wtih Type 2 Diabetes (DIPPER) pilot study is a phase II, open-label, single-arm, dose-escalation trial evaluating acetazolamide added to background SGLT2i therapy for 16 weeks. The study will evaluate the effect of acetazolamide on glomerular hyperfiltration, as measured by the acute, reversible change in measured GFR following each treatment period. The investigators will also study other important markers such as GFR recovery during washout periods, albuminuria, blood pressure, body weight, body composition, and safety and tolerability. The results of this study will help determine whether adding acetazolamide to SGLT2i therapy safely enhances SGLT2 inhibition's effects on renal hemodynamics, supporting its further evaluation as a potential treatment strategy for patients with T2D.
University Health Network, Toronto is the lead sponsor of 1,438 studies on the registry; 297 are open to participants now.
Of its 17 completed or terminated interventional studies of FDA-regulated products, 3 (18%) have results posted.
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Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HbA1c
A blood test of average blood sugar over the past two to three months, given as a percentage or in mmol/mol. 6.5% (48 mmol/mol) or more is the usual threshold for diabetes, normally confirmed by a second test.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GFR and eGFR (kidney filtering)
GFR (glomerular filtration rate) is how much blood the kidneys filter each minute. It is usually estimated from a blood test — eGFR, by formulas such as CKD-EPI or MDRD — and some studies ask for it to be measured directly instead. Usually given in mL/min/1.73 m².
Check the method, the units and the minimum the study states. A value of 90 or above is in the normal-or-high range, but kidney damage can show in other tests too.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
BMI (body mass index)
Weight in kilograms divided by height in metres squared. Example: 70 kg and 1.75 m gives 70 ÷ (1.75 × 1.75) ≈ 22.9.
What counts as overweight or obesity differs between countries (some use lower cut-offs), so go by the range the study states.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hypersensitivity
An allergy, or another reaction of the immune system, to a substance. “Hypersensitivity to the study drug” means a known allergic reaction to it — not every side effect a medicine can have.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ALT and AST (liver enzymes)
Two enzymes measured in a routine blood test of the liver. Higher levels can mean the liver is under strain or damaged. SGPT and SGOT are older names for ALT and AST.
Criteria usually give a limit as a multiple of the upper limit of normal (ULN), often higher when cancer has spread to the liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Bilirubin
A yellow substance made when red blood cells are broken down, which the liver clears. A high level can mean a problem with the liver or the bile ducts.
Criteria often allow more for people with Gilbert’s syndrome, a harmless inherited condition that raises bilirubin.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
ULN (upper limit of normal)
The top of the normal range for a blood test, as set by the laboratory that runs it. Each lab prints its own range next to your result.
“≤ 2.5 × ULN” means the result can be up to two and a half times that top value.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
TIA (transient ischaemic attack)
A “mini-stroke”: temporary stroke-like symptoms caused by reduced blood flow to part of the brain, spinal cord or eye, without signs of a new stroke on a scan.
Stroke symptoms need emergency care at once, even if they go away.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Patients will be up-titrated starting at acetazolamide 62.5 mg twice daily for 2 weeks, followed by a 2-week washout period. This sequence will be repeated with acetazolamide doses of 125 mg twice daily for 2 weeks and 250 mg twice daily for 2 weeks, with each treatment period followed by a 2-week washout period.
Drug: Acetazolamide 62.5 mg · Drug: Acetazolamide 125 mg · Drug: Acetazolamide 250 mg · Drug: Dapagliflozin 10mg
Oral acetazolamide 62.5 mg twice daily for 2 weeks
Oral acetazolamide 125 mg twice daily for 2 weeks
Oral acetazolamide 250 mg twice daily for 2 weeks
Oral dapagliflozin 10 mg once daily for 16 weeks
Iohexol Measured GFR
The primary outcome of this study is the absolute change in measured GFR during each 2-week course of acetazolamide, while on background dapagliflozin therapy. GFR will be measured using plasma clearance of the iohexol contrast agent. The initial "dip" in GFR was selected as the primary outcome as it provides an early and measurable indicator of the treatment effect on kidney physiology. A transient reduction in GFR is a known physiological response to both acetazolamide and SGLT2i, reflecting their effects on hyperfiltration. Assessing this early change allows evaluation of the immediate physiological response to combination therapy but also acts as an indicator of the potential longer-term renal benefits.
Time frame: From baseline to the end of treatment at 16 weeks
Measured GFR Recovery
Measured GFR through iohexol clearance will be used to determine GFR recovery to baseline following each washout period.
Time frame: From baseline to the end of treatment at 16 weeks
eGFR
Measured using spot urine and FMV urine collection for serum creatinine, standardized per 1.73m2 body surface area. And estimated using CKD-EPI 2021 equation.
Time frame: From baseline to the end of treatment at 16 weeks
Urine Albumin-to-Creatinine (UACR)
UACR will be quantified by measuring albumin and creatinine excretion using the average of three FMV samples.
Time frame: From baseline to the end of treatment at 16 weeks
Systolic Blood Pressure
Systolic blood pressure will be measured as per Hypertension Canada and assessed using an automated vital signs monitor (Connex Vital Signs Monitor, Welch Allyn).
Time frame: From baseline to the end of treatment at 16 weeks.
Diastolic Blood Pressure
Diastolic blood pressure will be measured as per Hypertension Canada and assessed using an automated vital signs monitor (Connex Vital Signs Monitor, Welch Allyn).
Time frame: From baseline to the end of treatment at 16 weeks
Change in Body Weight
Time frame: From baseline to the end of treatment at 16 weeks
Mean Arterial Pressure
Mean blood pressure will be measured as per Hypertension Canada and assessed using an automated vital signs monitor (Connex Vital Signs Monitor, Welch Allyn).
Time frame: From baseline to the end of treatment at 16 weeks
Percent Fat Mass
Bioimpedance analysis will be performed to determine percent body fat.
Time frame: From baseline to the end of treatment at 16 weeks
Percent Extracellular Fluid
Bioimpedance analysis will be performed to determine the percent extracellular fluid.
Time frame: From baseline to the end of treatment at 16 weeks
Percent Total Body Water
Bioimpedance analysis will be performed to determine percent total body water.
Time frame: From baseline to the end of treatment at 16 weeks
Incidence of Treatment-Emergent Adverse Events [Safety and Tolerability]
The side effects of acetazolamide and dapagliflozin have been well described and will be assessed at each study visit. Adverse events include acute kidney injury (AKI), volume depletion, hypokalemia, metabolic acidosis, hypoglycemia, and genitourinary infections. Frequent monitoring for adverse events has been integrated into the study design. All adverse events will be recorded on case report forms.
Time frame: From baseline to the end of treatment at 16 weeks
Plan to share: No
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From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
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Studies of the drug tested here: Acetazolamide
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