Lowered HbA1c in Individuals with Long-term Type 1 Diabetes Undergoing BCG Bladder
Cancer Therapy
H Dias, WM Kühtreiber, & DL Faustman. Massachusetts General Hospital & Harvard Medical School, Boston, MA, USA

INTRODUCTIONRESULTS• A double-blind Phase I clinical trial andopen-label trial have shown that adults with
type 1 diabetes (T1D) receiving repeat
bacillus Calmette-Guérin (BCG)
vaccinations experience statisticallysignificantly lowered HbA1c values over a
multi-year time course% CHANGE IN HBA1C AFTER BCG INSTILLATION FOR
BLADDER CANCER

A.

Data Source

No patients had a history of BCG
treatment/vaccination other than for
bladder cancer.

%Δ in A1cCombined
201010*-20
1230 1 2 3 4 5 6 70 1 2 3 4 5 6 7012

7.5

7.8

7.0

7.6

6.5

7.4

6.0

20

12

300-10-10-20
01Years2

30 1 2 3 4 5 6 7Years

-20

5.5

7.0
0 1 2 3 4 5 6 7012Years

T2D

*10

7.5

7.2

5.50Average A1c%Δ in A1c

10Years

0 1 2 3 4 5 6 7

3T2D117.27.2

10

7.0

7.0

96.8

6.8

86.6

6.6

76.4

60 1 2 3 4 5 6 7*

6.5

7.03T2D20

8.5

9.0

8.0

Years
T2DCombined
T1D

10.0-100OL

MGB*00-10MSA/Quest

T1D

Average A1c

T1D-20METHODS•

OL20• We investigated whether intravesicalinstillation of BCG for bladder cancer might
improve blood sugar levels in those withcomorbid T1D or type 2 diabetes (T2D)

We retrospectively analyzed three large
patient databases in the United States toassess BCG’s year-by-year impact on
HbA1c in subjects with documented T1D(N=19) or T2D (N=106) who underwent
BCG therapy for bladder cancer:
Management Sciences Associates/Quest
Diagnostics (MSA): N=263 million adults,
Massachusetts General Brigham (MGB):
N=6.5 million adults, Optum Labs (OL):
N=45 million adults

Data Source

MGB

MSA/Quest

T1D• BCG has also been used in the UnitedStates and Europe for early-stage bladdercancer, administered commonly as 6
intravesical doses for 6 weeks•AVERAGE CHANGE IN HBA1C AFTER BCG INSTILLATION FOR
BLADDER CANCER

B.

6.4

6.2012Years3*6.20 1 2 3 4 5 6 7Years0 1 2 3 4 5 6 7YearsFig 1. BCG therapy in adults with comorbid diabetes and bladder cancer was associated with multi-year and stable lowering of HbA1c in T1D, but not in T2D. (N for each dataset:
T1D: MSA=9, MGB=4, OL=6; T2D: MSA=9, MGB=97, OL=0) (A.) Lower HbA1c in T1D, but not T2D, post-BCG treatment for bladder cancer. In T1D, all three datasets show a reduction inHbA1c values (% change in HbA1c post-BCG instillation) and a near 10% decrease in HbA1cs at differing time points. The combined T1D data shows a statistically significant decrease in HbA1Cat Year 1 and Year 5 post-BCG (p = 0.0304, 0.0136). In T2D, MSA data shows no change and MGB data shows an increase in HbA1c values post-BCG instillation. The combined T2D dataindicates a significant increase in Year 4 after BCG instillation (p = 0.0223). (B.) Decreasing trends in average HbA1c for T1D, but not T2D. In T1D, lower HbA1cs are seen in all threedatabases for subjects treated with BCG for bladder cancer. When all three T1D datasets were combined, a Student’s paired t-test showed significance when comparing year 0 to year 5 (p =0.0133). In T2D, the trend is in an upwards direction post BCG instillation, a significant increase when comparing year 0 to year 4 (p = 0.0460).

CONCLUSIONS•Elderly patients with longstanding T1D who received high-dose intravesical BCG therapy as bladder cancer treatment show a gradual lowering of HbA1c, which is not seen inthose with T2D, likely due to metformin’s interference in BCG’s ability to change glycolysis pathways•

High-dose intravesical BCG therapy may contribute towards a drop in HbA1c values in T1D, consistent with interventional trials of the BCG vaccine in longstanding T1D
No conflicts of interest to declare.
Contact: dfaustman@mgh.harvard.edu
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