Nature of Business	3 Months Ended
Mar. 31, 2019
Accounting Policies [Abstract]
Nature of Business	1. Nature of Business GI Dynamics^® is a clinical stage medical device company focused on the development and commercialization of EndoBarrier, a medical device intended for treatment of patients with type 2 diabetes and obesity. Diabetes mellitus type 2 (also known as type 2 diabetes) is a long-term progressive metabolic disorder characterized by high blood sugar, insulin resistance, and reduced insulin production. According to the Centers for Disease Control and Prevention (CDC), people with type 2 diabetes represent 90% of the worldwide diabetes population, whereas 10% of this population is diagnosed with type 1 diabetes (a form of diabetes mellitus in which not enough insulin is produced). Being overweight is a condition where the patient’s body mass index (BMI) is greater than 25 (kg/m²); obesity is a condition where the patient’s BMI is greater than 30, according to the CDC. Obesity and its comorbidities contribute to the progression of type 2 diabetes. Many experts believe obesity contributes to higher levels of insulin resistance, which creates a feedback loop that increases the severity of type 2 diabetes. When considering treatment for type 2 diabetes, it is optimal to address obesity concurrently with diabetes. EndoBarrier^® is intended for the treatment of type 2 diabetes and obesity in a minimally invasive and reversible manner. The current treatment paradigm for type 2 diabetes is lifestyle therapy combined with pharmacological treatment, whereby treating clinicians prescribe a treatment regimen of one to four concurrent medications that could include insulin for patients with higher levels of blood sugar. Insulin carries a significant risk of increased mortality and may contribute to weight gain, which in turn may lead to higher levels of insulin resistance and increased levels of blood sugar. Fewer than 50% of patients treated pharmacologically for type 2 diabetes are adequately managed, meaning that medication does not lower blood sugar adequately and does not halt the progressive nature of diabetes of these patients. The current pharmacological treatment algorithms for type 2 diabetes fall short of ideal, creating a large and unfilled treatment gap. Our vision is to make EndoBarrierthe essential nonpharmacological and non-anatomy-altering treatment for patients with type 2 diabetes and obesity. We intend to achieve this vision by providing a safe and effective device, focusing on optimal patient care, supporting treating clinicians, adding to the extensive body of clinical evidence around EndoBarrier, gaining appropriate regulatory approvals, continuing to improve our products and systems, operating the company in a lean fashion, and maximizing shareholder value. EndoBarrier^® is intended for the treatment of type 2 diabetes and obesity in a minimally invasive and reversible manner and is designed to mimic the mechanism of action of duodenal-jejunal exclusion created by gastric bypass surgery. Since incorporation, the Company has devoted substantially all of its efforts to product commercialization, research and development, business planning, recruiting management and technical staff, acquiring operating assets, and raising capital. The Company currently operates in one reportable business segment. EndoBarrier History In 2011, the Company began commercial sales of its product, EndoBarrier, which was approved and commercially available in multiple countries outside the U.S. at the time. In 2013, the Company received approval from the U.S. Food and Drug Administration (“FDA”) to commence its initial pivotal trial of EndoBarrier (the “ENDO Trial”). The Company announced its decision to stop the ENDO Trial in the second half of fiscal year 2015 and thereafter announced that it was reducing headcount by approximately 46% as part of its efforts to restructure its business and expenses and to ensure sufficient cash remained available for it to establish new priorities, continue limited market development and research, and to evaluate strategic options. In the second and third quarters of fiscal year 2016, the Company took additional actions that it thought necessary to allow the opportunity to evolve its strategic options. These actions resulted in non-recurring charges totaling approximately $1.1 million, including $0.4 million related to restructuring charges in our second quarter, $0.6 million related to employee departures in both our second and third quarters and $0.1 million related to abandonment of our former headquarters in Lexington, MA. In October 2016, the Company received final cancellation notification from the Therapeutic Goods Administration (“TGA”) for the listing of EndoBarrier on the Australian Register of Therapeutic Goods (“ARTG”). In May 2017, the Company received notification from its notified body, SGS United Kingdom Limited (“SGS”), that the CE Mark for EndoBarrier had been suspended pending closure of non-conformances related to its quality management system required under International Organization for Standardization (“ISO”) regulations. On November 10, 2017, the Company received notification from SGS that SGS was withdrawing the Certificate of Conformance for EndoBarrier, ending the CE Marking of EndoBarrier in Europe and select Middle East countries. In December 2017, the Company received notification from the Medicines and Healthcare Products Regulatory Agency (“MHRA”) that all EndoBarrier delivery systems (liners) in inventory needed to be returned to the Company. In August 2018, the Company received approval of an investigational device exemption (“IDE”) from the FDA to begin enrollment in a pivotal trial evaluating the safety and efficacy of EndoBarrier in the United States pending Institutional Review Board (“IRB”) approval, which was received in February 2019. Financing History From its inception in 2003 to its initial public offering (“IPO”) in 2011, the Company was financed by a series of preferred stock financings. In September 2011, the Company completed its IPO of common stock in the form of CHESS Depositary Interests (“CDIs”) in Australia. As a result of the IPO and simultaneous private placement in the U.S., the Company raised a total of approximately $72.5 million in proceeds, net of expenses and repayment of $6.0 million of the Company’s convertible term promissory notes. Additionally, in July and August 2013, the Company issued CDIs on the Australian Securities Exchange (“ASX”) through a private placement and share purchase plan, which raised a total of approximately $52.5 million, net of expenses. In May 2014, the Company raised an additional total of approximately $30.8 million, net of expenses, when it issued CDIs on the ASX through a private placement. On December 20, 2016, the Company completed a private placement issue of 69,865,000 CDIs (1,397,300 shares) at an issue price of A$0.022 per CDI raising approximately $1.0 million, net of issuance costs. In January 2017, the Company completed the issue of 12,481,600 CDIs (249,632 shares) to eligible investors under a Security Purchase Plan for approximately $0.83 per share of common stock (A$0.022 per CDI) resulting in net proceeds after issuance costs of approximately $0.2 million. In June 2017, the Company completed a Convertible Term Promissory Note (the “2017 Note”) secured financing with its largest shareholder Crystal Amber Fund Limited (“Crystal Amber”) for a gross amount of $5.0 million. The 2017 Note accrues interest at 5% per annum compounded annually. Crystal Amber is deemed a Related Party of the Company for ASX purposes due to the size of its ownership position. The 2017 Note was originally due on December 31, 2018 and contains provisions for conversion during its term and is also subject to security arrangements in favor Crystal Amber (See Note 10 of the Consolidated Financial Statements for a more complete description of the terms and conditions of the financing). In January and March 2018, the Company raised approximately $1.6 million in an offering of its CDIs to sophisticated and professional investors, including certain existing investors in Australia, the United States and the United Kingdom. In May 2018, the Company completed a Convertible Term Promissory Note (the “2018 Note”) and Warrant (the “2018 Warrant”) financing with its largest shareholder Crystal Amber for a gross amount of $1.75 million. The 2018 Note accrues interest at 10% per annum compounded annually. The 2018 Note matures and the 2018 Warrant expires on May 30, 2023. Crystal Amber is deemed a Related Party of the Company for ASX purposes due to the size of its ownership position. (See Note 10 of the Consolidated Financial Statements for a more complete description of the terms and conditions of the financing). In September 2018, the Company received commitments for a private placement of approximately $5 million in an offering of its CDIs to sophisticated and professional investors, including certain existing investors in Australia, the United States and the United Kingdom. The first tranche of $2.2 million closed and cash was received in September 2018. The second and final tranche of $2.8 million was contingent upon shareholder approval, which was obtained in October 2018. Cash proceeds were received in November 2018. In December 2018, the maturity date of the 2017 Note was extended from December 31, 2018 to March 31, 2019 in exchange for payment of $394 thousand, the total accrued interest on the 2017 Note at December 31, 2018. In March 2019, the Company completed a Convertible Term Promissory Note (the “March 2019 Note”) and Warrant (the “March 2019 Warrant”) financing with its largest shareholder, Crystal Amber, for a gross amount of $1.0 million. The March 2019 Note accrues interest at 10% per annum compounded annually. Certain specific terms associated with the conversion of the March 2019 Note and issuance of the March 2019 Warrant require shareholder approval, which will be sought in a vote of the stockholders of the Company during the Annual Meeting of Stockholders anticipated to be held in May or June 2019. The March 2019 Note matures on March 15, 2024 and the March 2019 Warrant, if issued, will expire on the fifth anniversary of the date of issuance. Crystal Amber is deemed a Related Party of the Company for ASX purposes due to the size of its ownership position. (See Note 10 of the Consolidated Financial Statements for a more complete description of the terms and conditions of the financing). In March 2019, the maturity date of the 2017 Note was extended to May 1, 2019. In April 2019, the maturity date of the 2017 Note was extended to July 1, 2019. In May 2019, the Company completed a Convertible Term Promissory Note (the “May 2019 Note”) and Warrant (the “May 2019 Warrant”) financing with its largest shareholder, Crystal Amber, for a gross amount of up to $3.0 million. The May 2019 Note accrues interest at 10% per annum, computed daily until the date upon which full funding under the May 2019 Note is anticipated to be received, regardless of whether full funding is made on such date (the “Full Funding Date”) and compounded annually beginning on the Full Funding Date. The $3.0 million payment will be made in several tranches. Certain specific terms associated with the conversion of the May 2019 Note and issuance of the May 2019 Warrant require shareholder approval, which will be sought in a vote of the stockholders of the Company during the Annual Meeting of Stockholders anticipated to be held in May or June 2019. The May 2019 Note matures and the May 2019 Warrant, if issued, will expire on the fifth anniversary of the Full Funding Date. Crystal Amber is deemed a Related Party of the Company for ASX purposes due to the size of its ownership position. (See Note 10 of the Consolidated Financial Statements for a more complete description of the terms and conditions of the financing). Going Concern As of March 31, 2019, the Company’s primary source of liquidity is its cash and cash equivalents balances. The Company continues to evaluate which markets are appropriate to pursue regulatory approvals, continue pursuing reimbursement, market awareness and general market development and selling efforts. The Company continues to restructure its business and costs, establish new priorities, and evaluate strategic options. As a result, if the Company remains in business, it expects to incur significant operating losses for the next several years. The Company has incurred operating losses since inception and at March 31, 2019 had an accumulated deficit of approximately $270 million, a working capital deficit of approximately $5.5 million, cash used in operating activities of approximately $3.5 million and cash and cash equivalents of approximately $1.3 million. Cash provided by these activities will be used predominantly to prepare for the Company’s clinical trial, which will result in increased expenses. The Company does not expect its current cash balances will be sufficient to operate beyond July 1, 2019 if cash is required to settle the 2017 Note on that date. Both parties to the 2017 Note are aware that if the Company is required to make this payment on the due date of July 1, 2019, the Company will be required either to renegotiate the due date of the loan or potentially cease operations. Crystal Amber and the Company are in discussions to extend of the due date of the 2017 Note, but there can be no assurance that any extension will occur. If the Company is able to amend the terms of the 2017 Note, it believes its cash and cash equivalents will be sufficient to fund operations to the end of August 2019, or until the modified due date of the note. The Company will need to raise additional funds through any combination of collaborative arrangements, strategic alliances, and additional equity and debt financings or from other sources. The Company has no guaranteed source of capital that will sustain operations beyond August 2019. There can be no assurance that other potential financing opportunities will be available on acceptable terms, if at all. As such, if access to capital is not achieved to satisfy cash needs in the near term, the Company’s business, financial condition and results of operations will be materially harmed or the Company may be required to cease operations. These factors raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued. The accompanying consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and liabilities and commitments in the normal course of business. The consolidated financial statements as of March 31, 2019 and December 31, 2018 and the three months ended March 31, 2019 and 2018 do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result from uncertainty related to the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued.

Nature of Business

3 Months Ended

Mar. 31, 2019

1. Nature of Business

GI Dynamics^® is a clinical stage medical device company focused on the development and commercialization of EndoBarrier, a medical device intended for treatment of patients with type 2 diabetes and obesity.

Diabetes mellitus type 2 (also known as type 2 diabetes) is a long-term progressive metabolic disorder characterized by high blood sugar, insulin resistance, and reduced insulin production. According to the Centers for Disease Control and Prevention (CDC), people with type 2 diabetes represent 90% of the worldwide diabetes population, whereas 10% of this population is diagnosed with type 1 diabetes (a form of diabetes mellitus in which not enough insulin is produced).

Being overweight is a condition where the patient’s body mass index (BMI) is greater than 25 (kg/m²); obesity is a condition where the patient’s BMI is greater than 30, according to the CDC. Obesity and its comorbidities contribute to the progression of type 2 diabetes. Many experts believe obesity contributes to higher levels of insulin resistance, which creates a feedback loop that increases the severity of type 2 diabetes.

When considering treatment for type 2 diabetes, it is optimal to address obesity concurrently with diabetes.

EndoBarrier^® is intended for the treatment of type 2 diabetes and obesity in a minimally invasive and reversible manner.

The current treatment paradigm for type 2 diabetes is lifestyle therapy combined with pharmacological treatment, whereby treating clinicians prescribe a treatment regimen of one to four concurrent medications that could include insulin for patients with higher levels of blood sugar. Insulin carries a significant risk of increased mortality and may contribute to weight gain, which in turn may lead to higher levels of insulin resistance and increased levels of blood sugar. Fewer than 50% of patients treated pharmacologically for type 2 diabetes are adequately managed, meaning that medication does not lower blood sugar adequately and does not halt the progressive nature of diabetes of these patients.

The current pharmacological treatment algorithms for type 2 diabetes fall short of ideal, creating a large and unfilled treatment gap.

Our vision is to make EndoBarrierthe essential nonpharmacological and non-anatomy-altering treatment for patients with type 2 diabetes and obesity. We intend to achieve this vision by providing a safe and effective device, focusing on optimal patient care, supporting treating clinicians, adding to the extensive body of clinical evidence around EndoBarrier, gaining appropriate regulatory approvals, continuing to improve our products and systems, operating the company in a lean fashion, and maximizing shareholder value.

EndoBarrier^® is intended for the treatment of type 2 diabetes and obesity in a minimally invasive and reversible manner and is designed to mimic the mechanism of action of duodenal-jejunal exclusion created by gastric bypass surgery.

Since incorporation, the Company has devoted substantially all of its efforts to product commercialization, research and development, business planning, recruiting management and technical staff, acquiring operating assets, and raising capital. The Company currently operates in one reportable business segment.

EndoBarrier History

In 2011, the Company began commercial sales of its product, EndoBarrier, which was approved and commercially available in multiple countries outside the U.S. at the time.

In 2013, the Company received approval from the U.S. Food and Drug Administration (“FDA”) to commence its initial pivotal trial of EndoBarrier (the “ENDO Trial”). The Company announced its decision to stop the ENDO Trial in the second half of fiscal year 2015 and thereafter announced that it was reducing headcount by approximately 46% as part of its efforts to restructure its business and expenses and to ensure sufficient cash remained available for it to establish new priorities, continue limited market development and research, and to evaluate strategic options.

In the second and third quarters of fiscal year 2016, the Company took additional actions that it thought necessary to allow the opportunity to evolve its strategic options. These actions resulted in non-recurring charges totaling approximately $1.1 million, including $0.4 million related to restructuring charges in our second quarter, $0.6 million related to employee departures in both our second and third quarters and $0.1 million related to abandonment of our former headquarters in Lexington, MA.

In October 2016, the Company received final cancellation notification from the Therapeutic Goods Administration (“TGA”) for the listing of EndoBarrier on the Australian Register of Therapeutic Goods (“ARTG”).

In May 2017, the Company received notification from its notified body, SGS United Kingdom Limited (“SGS”), that the CE Mark for EndoBarrier had been suspended pending closure of non-conformances related to its quality management system required under International Organization for Standardization (“ISO”) regulations.

On November 10, 2017, the Company received notification from SGS that SGS was withdrawing the Certificate of Conformance for EndoBarrier, ending the CE Marking of EndoBarrier in Europe and select Middle East countries.

In December 2017, the Company received notification from the Medicines and Healthcare Products Regulatory Agency (“MHRA”) that all EndoBarrier delivery systems (liners) in inventory needed to be returned to the Company.

In August 2018, the Company received approval of an investigational device exemption (“IDE”) from the FDA to begin enrollment in a pivotal trial evaluating the safety and efficacy of EndoBarrier in the United States pending Institutional Review Board (“IRB”) approval, which was received in February 2019.

Financing History

From its inception in 2003 to its initial public offering (“IPO”) in 2011, the Company was financed by a series of preferred stock financings. In September 2011, the Company completed its IPO of common stock in the form of CHESS Depositary Interests (“CDIs”) in Australia. As a result of the IPO and simultaneous private placement in the U.S., the Company raised a total of approximately $72.5 million in proceeds, net of expenses and repayment of $6.0 million of the Company’s convertible term promissory notes. Additionally, in July and August 2013, the Company issued CDIs on the Australian Securities Exchange (“ASX”) through a private placement and share purchase plan, which raised a total of approximately $52.5 million, net of expenses. In May 2014, the Company raised an additional total of approximately $30.8 million, net of expenses, when it issued CDIs on the ASX through a private placement.

On December 20, 2016, the Company completed a private placement issue of 69,865,000 CDIs (1,397,300 shares) at an issue price of A$0.022 per CDI raising approximately $1.0 million, net of issuance costs. In January 2017, the Company completed the issue of 12,481,600 CDIs (249,632 shares) to eligible investors under a Security Purchase Plan for approximately $0.83 per share of common stock (A$0.022 per CDI) resulting in net proceeds after issuance costs of approximately $0.2 million.

In June 2017, the Company completed a Convertible Term Promissory Note (the “2017 Note”) secured financing with its largest shareholder Crystal Amber Fund Limited (“Crystal Amber”) for a gross amount of $5.0 million. The 2017 Note accrues interest at 5% per annum compounded annually. Crystal Amber is deemed a Related Party of the Company for ASX purposes due to the size of its ownership position. The 2017 Note was originally due on December 31, 2018 and contains provisions for conversion during its term and is also subject to security arrangements in favor Crystal Amber (See Note 10 of the Consolidated Financial Statements for a more complete description of the terms and conditions of the financing).

In January and March 2018, the Company raised approximately $1.6 million in an offering of its CDIs to sophisticated and professional investors, including certain existing investors in Australia, the United States and the United Kingdom.

In May 2018, the Company completed a Convertible Term Promissory Note (the “2018 Note”) and Warrant (the “2018 Warrant”) financing with its largest shareholder Crystal Amber for a gross amount of $1.75 million. The 2018 Note accrues interest at 10% per annum compounded annually. The 2018 Note matures and the 2018 Warrant expires on May 30, 2023. Crystal Amber is deemed a Related Party of the Company for ASX purposes due to the size of its ownership position. (See Note 10 of the Consolidated Financial Statements for a more complete description of the terms and conditions of the financing).

In September 2018, the Company received commitments for a private placement of approximately $5 million in an offering of its CDIs to sophisticated and professional investors, including certain existing investors in Australia, the United States and the United Kingdom. The first tranche of $2.2 million closed and cash was received in September 2018. The second and final tranche of $2.8 million was contingent upon shareholder approval, which was obtained in October 2018. Cash proceeds were received in November 2018.

In December 2018, the maturity date of the 2017 Note was extended from December 31, 2018 to March 31, 2019 in exchange for payment of $394 thousand, the total accrued interest on the 2017 Note at December 31, 2018.

In March 2019, the Company completed a Convertible Term Promissory Note (the “March 2019 Note”) and Warrant (the “March 2019 Warrant”) financing with its largest shareholder, Crystal Amber, for a gross amount of $1.0 million. The March 2019 Note accrues interest at 10% per annum compounded annually. Certain specific terms associated with the conversion of the March 2019 Note and issuance of the March 2019 Warrant require shareholder approval, which will be sought in a vote of the stockholders of the Company during the Annual Meeting of Stockholders anticipated to be held in May or June 2019. The March 2019 Note matures on March 15, 2024 and the March 2019 Warrant, if issued, will expire on the fifth anniversary of the date of issuance. Crystal Amber is deemed a Related Party of the Company for ASX purposes due to the size of its ownership position. (See Note 10 of the Consolidated Financial Statements for a more complete description of the terms and conditions of the financing).

In March 2019, the maturity date of the 2017 Note was extended to May 1, 2019. In April 2019, the maturity date of the 2017 Note was extended to July 1, 2019.

In May 2019, the Company completed a Convertible Term Promissory Note (the “May 2019 Note”) and Warrant (the “May 2019 Warrant”) financing with its largest shareholder, Crystal Amber, for a gross amount of up to $3.0 million. The May 2019 Note accrues interest at 10% per annum, computed daily until the date upon which full funding under the May 2019 Note is anticipated to be received, regardless of whether full funding is made on such date (the “Full Funding Date”) and compounded annually beginning on the Full Funding Date. The $3.0 million payment will be made in several tranches. Certain specific terms associated with the conversion of the May 2019 Note and issuance of the May 2019 Warrant require shareholder approval, which will be sought in a vote of the stockholders of the Company during the Annual Meeting of Stockholders anticipated to be held in May or June 2019. The May 2019 Note matures and the May 2019 Warrant, if issued, will expire on the fifth anniversary of the Full Funding Date. Crystal Amber is deemed a Related Party of the Company for ASX purposes due to the size of its ownership position. (See Note 10 of the Consolidated Financial Statements for a more complete description of the terms and conditions of the financing).

Going Concern

As of March 31, 2019, the Company’s primary source of liquidity is its cash and cash equivalents balances. The Company continues to evaluate which markets are appropriate to pursue regulatory approvals, continue pursuing reimbursement, market awareness and general market development and selling efforts. The Company continues to restructure its business and costs, establish new priorities, and evaluate strategic options. As a result, if the Company remains in business, it expects to incur significant operating losses for the next several years.

The Company has incurred operating losses since inception and at March 31, 2019 had an accumulated deficit of approximately $270 million, a working capital deficit of approximately $5.5 million, cash used in operating activities of approximately $3.5 million and cash and cash equivalents of approximately $1.3 million. Cash provided by these activities will be used predominantly to prepare for the Company’s clinical trial, which will result in increased expenses. The Company does not expect its current cash balances will be sufficient to operate beyond July 1, 2019 if cash is required to settle the 2017 Note on that date. Both parties to the 2017 Note are aware that if the Company is required to make this payment on the due date of July 1, 2019, the Company will be required either to renegotiate the due date of the loan or potentially cease operations. Crystal Amber and the Company are in discussions to extend of the due date of the 2017 Note, but there can be no assurance that any extension will occur. If the Company is able to amend the terms of the 2017 Note, it believes its cash and cash equivalents will be sufficient to fund operations to the end of August 2019, or until the modified due date of the note. The Company will need to raise additional funds through any combination of collaborative arrangements, strategic alliances, and additional equity and debt financings or from other sources.

The Company has no guaranteed source of capital that will sustain operations beyond August 2019. There can be no assurance that other potential financing opportunities will be available on acceptable terms, if at all. As such, if access to capital is not achieved to satisfy cash needs in the near term, the Company’s business, financial condition and results of operations will be materially harmed or the Company may be required to cease operations. These factors raise substantial doubt about the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued.

The accompanying consolidated financial statements have been prepared assuming the Company will continue as a going concern, which contemplates the realization of assets and liabilities and commitments in the normal course of business. The consolidated financial statements as of March 31, 2019 and December 31, 2018 and the three months ended March 31, 2019 and 2018 do not include any adjustments to reflect the possible future effects on the recoverability and classification of assets or the amounts and classification of liabilities that may result from uncertainty related to the Company’s ability to continue as a going concern within one year after the date that the financial statements are issued.