4Confidential – For Internal Use Only

SAFE HARBOR STATEMENT

This presentation contains “forward” looking statements that are based on our management’s beliefs and assumptions and on information currently available to management. We intend for such forward-looking statements to be covered by the safe harbor provisions for forward-looking statements contained in the U.S. Private Securities Litigation Reform Act of 1995. Forward-looking statements include information concerning our possible or assumed strategy, future operations, financing plans, operating model, financial position, future revenues, projected costs, competitive position, industry environment, potential growth opportunities, potential market opportunities, plans and objectives of management and the effects of competition on our business. These also include statements with respect to the impacts of the COVID-19 pandemic on Dexcom. The presentation also contains estimates and other statistical data made by independent parties relating to market size and growth and other data about our industry. This data involves a number of assumptions and limitations, and you are cautioned not to give undue weight to such estimates.

Forward-looking statements include all statements that are not historical facts and can be identified by terms such as “anticipates,” “believes,” “could,” “seeks,” “estimates,” “targets,” “guidance,” “expects,” “intends,” “may,” “plans,” “potential,” “predicts,” “prospects,” “projects,” “should,” “will,” “would” or similar expressions and the negatives of those terms, although not all forward-looking statements contain these identifying words.

Forward-looking statements involve known and unknown risks, uncertainties and other factors that may cause our actual results, performance or achievements to be materially different from any future results, performance or achievements expressed or implied by the forward-looking statements. We cannot guarantee that we will achieve the plans, intentions, or expectations disclosed in our forward-looking statements, and you should not place undue reliance on our forward-looking statements.

The risks and uncertainties that may cause actual results to differ materially from DexCom’s current expectations are more fully described in DexCom’s annual report on Form 10-K for the period ended December 31, 2019, as filed with the Securities and Exchange Commission on February 13, 2020, its most recent quarterly report on Form 10-Q for the period ended September 30, 2020, as filed with the Securities and Exchange Commission on October 27, 2020, and its other reports, each as filed with the Securities and Exchange Commission. DexCom assumes no obligation to update any such forward-looking statement after the date of this report or to conform these forward-looking statements to actual results.

DexCom reports non-GAAP financial measures in addition to, and not as a substitute for, or superior to, measures of financial performance prepared in accordance with GAAP. These non-GAAP financial measures are not based on any comprehensive set of accounting rules or principles, differ from GAAP measures with the same names, and may differ from non-GAAP financial measures with the same or similar names that are used by other companies. We believe that non-GAAP financial measures should only be used to evaluate our results of operations in conjunction with the corresponding GAAP financial measures. We encourage investors to carefully consider our results under GAAP, as well as our supplemental non-GAAP information and the reconciliations between these presentations, to more fully understand our business.

KEVIN SAYERChairman, President and CEO

7Confidential – For Internal Use Only

DEXCOM: A STORY OF SUSTAINABLE GROWTH

Total Revenue

$49 $76 $100 $160$259

$402

$573$719

$1,032

$1,476

$1,900E

$0

$400

$800

$1,200

$1,600

$2,000

2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 2020E

RE

VE

NU

E (

$M

M)

10-Year CAGR: 44%

8Confidential – For Internal Use Only

2018 INVESTOR DAY: PREVIOUS 5-YEAR FINANCIAL TARGETS

We are closing in on our 5-year targets after only two years:2020E Guidance - $1.9B Revenue and 26% Adj. EBITDA Margin

2023 Revenue LRP

$2.0 – 2.5 Billion(15 – 20% CAGR)

Scale and Profitability

2023 Adj. EBITDA Margin Target: 25%

9Confidential – For Internal Use Only

2020 INVESTOR DAY: NEW DEXCOM FINANCIAL TARGETS

Upside opportunities to 2025 base case include faster adoption in: Hospital / Patient Monitoring, Pregnancy, Emerging Markets

2025 Revenue LRP

$4.0 – 4.5 Billion(~15 – 20% CAGR)

Includes low-to-mid teens growth for global IIT

Scale and Profitability

2025 Adj. EBITDA Margin Target: 30%

Scaling efficiently to support long-term growth

10Confidential – For Internal Use Only

DEXCOM IS EMBRACING AN AGGRESSIVE GROWTH STRATEGY

US IITOur heritage andlargest business

Global ExpansionGrowing our global presence

Type 2 Non-IntensiveInitial commercial efforts

underway

…While laying the foundation for several long-term TAM extensions

11Confidential – For Internal Use Only

A GLOBAL CRISIS THAT REMAINS UNCONTROLLED

Diabetes Diagnosis and CostAdults (aged 20-79) with Diabetes Globally

151Min 2000

Source: IDF Atlas, 9th edition (2019)).

463Min 2019

700Min 2045E

Global Diabetes RelatedHealth Expenditures

$760Bin 2019

13Confidential – For Internal Use Only

MOMENTUM CONTINUES IN US IIT*

13

Expanding Reimbursement – Especially T2 IIT

Proven Outcomes

*IIT = Intensive Insulin Therapy or patients using mealtime insulin

Right Product

14Confidential – For Internal Use Only

US IIT: ROOM FOR SIGNIFICANT GROWTH

Note: IIT = Intensive insulin therapy, those whose insulin regimen includes mealtime insulin. 4M estimate sourced from CDC (Type 1) and third-party script data (Type 2 IIT). 1) Based on internal estimates and third-party data providers as of 09/30/20. Includes users of flash glucose monitors (FGM or intermittently scanned CGM).

Core Intensive Business Estimated CGM Market Penetration1

~4 MillionPeople

(~1.6 T1; ~2.4 T2 IIT)

~15%

~40%

~25%

U.S. Type 1

U.S. Type 2 Intensive

U.S. IIT

15Confidential – For Internal Use Only

LEADING THE WAY IN CONNECTED TECHNOLOGY

*Conceptual image

Insulin Pumps

Smart Insulin Pens

Insulin Patch Pumps

16Confidential – For Internal Use Only

FROM CLINICAL OUTCOMES TO COMMERCIAL PRESENCERoutes to expand the use of Dexcom CGM for Non-Intensive Type 2

Patients Payers

Programs Providers

Non-Intensive T2:

~30 Million People in the US1

More than 7x the patient TAM of our

current IIT business

1) Data from CDC 2020 diabetes statistics report, total people with diabetes less estimate of 4 million IIT.

17Confidential – For Internal Use Only

TYPE 2 DIABETES: 3 ELEMENTS OF AN EFFECTIVE SOLUTION

UserEngagement

Return on Investment

Health Outcomes

18Confidential – For Internal Use Only

• 90% reported that real-time CGM use contributed to a healthier lifestyle

• 87% changed their food choices based on real-time CGM data

Real-time CGM and Behavior Modification1

Dexcom CGM and Disease Management2

User Satisfaction among CGM naïve3

• 95% feel wearing Dexcom CGM makes it easier to perform self-care behaviors

• 80% of members feel Dexcom CGM helps control diabetes (even when not wearing it)

DEXCOM CGM IS EMPOWERING USERS

• 96% had not used a CGM before

• 93% said Dexcom G6 comfortable to wear

1) Ehrhardt N. and Al Zaghal E., “Continuous Glucose Monitoring As a Behavior Modification Tool,” Diabetes Care 38 (2020). Published online January 9, 2020. 2) Data presented at ATTD in 2020 based on 594 survey participants. See https://www.businesswire.com/news/home/20200222005012/en/Onduo-Presents-Data-High-Satisfaction-Positive-Glycemic 3) Dexcom internal pilot, n=140.

19Confidential – For Internal Use Only

TYPE 2 OUTCOMES: DEXCOM CGM AS A CORE DRIVER OF PROGRAMMATIC SOLUTIONS

1) https://www.businesswire.com/news/home/20200713005172/en/Innovative-New-Level2%E2%84%A2-Digital-Health-Therapy-Resulted; https://onduo.com/cgmwhitepaper/;updated medication data from Level2.

2) Layne JE, et al. Change in A1C With and Without Intermittent Use of CGM In Adults With Type 2 Diabetes Participating in the Onduo Virtual Diabetes Clinic. Diabetes. 2020.

3) Polonsky WH, et al. The Impact of Participation in a Virtual Diabetes Clinic on Diabetes-Related Distress in Individuals with Type 2 Diabetes. Clinical Diabetes, ePub June 12, 2020.

4) Majithia AR, et al. Improved A1c and TIR in Adults With T2D Participating in a CGM Driven Virtual Diabetes Clinic. Diabetes. 2020

Digital Health therapy of UnitedHealthcare, utilizing Dexcom CGM as an essential component

Initial pilot of 790 members saw1:

• Greater than 1% average A1c reduction within 90 days for those whose baseline was above 8%

• Eliminated the need for >650 prescriptions

• Some members achieved remission with no further need for Type 2 medication

~2x greater A1c reduction for those with baseline A1c greater than 8%2

Significantly greater reduction in diabetes distress3

Time-in-range increased by 2.4 hours per day4

Significant reductions to weight, blood pressure and cholesterol4

CGM results versus standard of care (BGM) in the Onduo virtual diabetes clinic:

20Confidential – For Internal Use Only

OUR SOLUTION MUST ADDRESS THE COST CRISIS

1) Total healthcare costs for people with diabetes, divided by total US people diagnosed with diabetes. Source: 2007, 2012, and 2017 ADA Economic Cost of Diabetes Reports (Diabetes Care). 2030 amount applies 3.6% annual CAGR calculated between 2007-2017 thru the year 2030. 2) 2017 ADA Economic Cost of Diabetes.

People diagnosed with diabeteshave ~2.3x higher expensesthan those without2

More than 1 in 4 U.S. health care dollars are spent on people with diabetes2

$11,729 $13,735

$16,778

$27,000

$0

$5,000

$10,000

$15,000

$20,000

$25,000

$30,000

U.S. Annual Healthcare Costs per Person with Diabetes1

2007 2012 2017 2030E

21Confidential – For Internal Use Only

DEXCOM CGM DRIVEN OUTCOMES: TYPE 2 DIABETES

$417 per member per month savings: Dexcom G6 vs. Standard of Care1

Reduced ER Visits Less Primary Care / Specialty Visits

Better Glucose Management (A1c

reduction)

Reduction to BMI (Cumulative)

Less Labs Ordered

1) Cost comparison based on SelectHealth non-Medicare Advantage customers. For the published results see Isaacson B, Kaufusi S, Sorensen J, et al. Demonstrating the Clinical Impact of Continuous Glucose Monitoring Within an Integrated Healthcare Delivery System. Journal of Diabetes Science and Technology. September 2020.

22Confidential – For Internal Use Only

OUS REMAINS A SIGNIFICANT GROWTH OPPORTUNITY FOR DEXCOM

Dexcom’s core IIT market consists of ~10 million people globally and remains underpenetrated

Note: IIT = Intensive insulin therapy, those whose insulin regimen includes mealtime insulin.Core Market defined as: US, Canada, Western Europe, Australia, New Zealand, South Korea and Japan.

Core market Early-stage presence

New opportunity

23Confidential – For Internal Use Only

SIGNIFICANT MARKET EXTENSIONS AHEAD

1: U.S. births per year, of which the rate of gestational diabetes is ~5-10%.2: Dexcom estimate for annual number of US patients experiencing disglycemia. Cook CB, Kongable GL, Potter DJ, Abad VJ, Leija DE, Anderson M. Inpatient glucose control: a glycemic survey of 126 U.S. hospitals. J Hosp Med. 2009;4(9):E7–E14.3. Sg2 2020 Impact of Change® report.

4: https://www.cdc.gov/diabetes/data/statistics-report/index.html

Total Market Size – U.S. Patients

~4 million / yrPregnancy1

>14 million / yrInpatient Hospital2

88 millionPrediabetes4

10-Yr CAGR (est.): 15%Home Care3

25Confidential – For Internal Use Only

“THIS TECHNOLOGY GIVES PEOPLE HOPE.”

“Okay, wait. I’ve had too much sugar for today, I need to drink some water. I need to relax, take some deep breaths, de-stress, help my body

come back into alignment.”

“Because then I would know exactly when it was going up and what I could

do at that moment to change it, to help out.”

“That’s what people need, real-time data.”

“Holds you accountable for that moment.”

“It allows me a better look-see at the types of foods and the types of activities that I’m doing.”

“So if it uses an app on my phone that could

actually help me track [my blood sugar] and generate that kind of data…that would be

awesome.”

“To see where, with my diet changing, how things

have changed.”

I had an aunt with diabetes that lost both her feet. I thought if I am going to be here at 77, I need my feet, I need my eyes. I have nothing to lose… and feet and eyes and kidneys to gain by taking control of my diabetes.