A phase 2a trial randomized, double-blind, placebo-controlled, parallel group trial to determine whether NMN administration improves DKD, as indicated by a significantly greater reduction in UACR compared with placebo administration. Eligible participants will be randomized to receive either 1000 mg NMN or placebo twice daily.

This will be two centers, randomized, double-blind, placebo-controlled, parallel group trial to determine whether βNMN, after its daily oral administration, is associated with a greater reduction in the UACR compared to placebo.

The trial will enroll community-dwelling older adults, 60 years or older, with type 2 diabetes mellitus (T2DM) and urine albumin to creatinine excretion ratio > 100 mg/ g creatinine.

Inclusion Criteria:

1. A man or a postmenopausal woman (complete cessation of menses for one or more years and /or FSH > 20 U/L), 30 years or older

2. Has type 1 or type 2 diabetes mellitus, as indicated by any of the following:

   1. Self-report of type 1 or type 2 diabetes plus the use of a prescribed medication.
   2. ICD-10 code for type 1 or type 2 diabetes plus current use of a medication in the electronic medical record.
   3. HbA1c >6.4%; or 2 fasting glucose > 125 mg/dL

3. Has an average of two or more morning UACR equal to or above 100mg/g creatinine each of which must be equal to or greater than 60 mg / g creatinine with at least one UACR value measured during the screening visit.

   a. Recent UACR value in the medical record within the preceding 3 months prior to screening is acceptable.

4. If type 2 diabetic and UACR is > 300 mg/g creatinine, must be currently using an ACE inhibitor or an ARB or a SGLT2 inhibitor.

5. eGFR > 25 mL/ min / 1.73 m2

6. Hemoglobin A1c <10%

7. Able to speak English or Spanish or Haitian Creole

8. Willing and able to provide written informed consent

9. In addition, female participants must Not be pregnant and not planning to become pregnant over the next 6 months.

Exclusion criteria:

1. Fasting morning UACR > 5,000 mg/ g creatinine

2. Other laboratory abnormalities:

   1. Has AST or ALT > 3 times the upper limit of normal
   2. eGFR < 25 mL/ min / 1.73 m2
   3. Hematocrit < 0.34 or > 0.50 L/L

3. A major adverse cardiovascular event in preceding 3 months

4. Participation in an investigational trial to evaluate pharmaceuticals or biologics within the past 3 months or 5 half-lives, whichever is shorter

5. Current alcohol or substance use disorder or dependence (DSM 5 criteria).

6. Major depressive disorder, bipolar disorder, schizophrenia, or current psychotic symptoms or behavioral problems that could interfere with study procedures.

7. An acute illness, including COVID-19, requiring hospitalization within the past 3 months or any acute illness, including COVID-19, within the past month.

8. Has a history of anaphylaxis from vitamin B3 derivatives

9. BMI > 42.5 kg/ m2

10. If patient has a confirmed diagnosis of type 3 diabetes, or gestational diabetes.

Individual participant data will not be shared

The study is double-blind in that the study participants and the study staff involved in outcomes assessments will be unaware of the intervention assignment. The randomization schedule will be masked from all study personnel except those specifically designated below.

1. The unblinded study biostatistician
2. The staff of the Investigational Drug Pharmacy Services.
3. The DSMB, if requested