Medical diagnosis of CGL can be made after observing the physical symptoms of the disease: lipoatrophy (loss of fat tissues) affecting the trunk, limbs, and face; hepatomegaly; acromegaly; insulin resistance; and high serum levels of triglycerides. Genetic testing can also confirm the disease, as mutations in the AGPAT2 gene is indicative of CGL1, a mutation in the BSCL2 gene is indicative of CGL2, and mutations in the CAV1 and PTRF genes are indicative of CGL3 and CGL4 respectively. Physical diagnosis of CGL is easier, as CGL patients are recognizable from birth, due to their extreme muscular appearance, which is caused by the absence of subcutaneous fat.

CGL3 patients have serum creatine kinase concentrations much higher than normal (2.5 to 10 times the normal limit). This can be used to diagnose type 3 patients and differentiate them from CGL 1 and 2 without mapping their genes. Additionally, CGL3 patients have low muscle tone when compared with other CGL patients.

The diagnosis of the disease is mainly clinical (see diagnostic criteria). A laboratory workup is needed primarily to investigate for the presence of associated disorders (metabolic, autoimmune, and renal diseases).

- Every patient should have a fasting blood glucose and lipid profile, creatinine evaluation, and urinalysis for protein content at the first visit, after which he/she should have these tests on a regular basis.

- Although uncommon, lipid abnormalities can occur in the form of raised triglyceride levels and low high-density lipoprotein cholesterol levels.

- Patients usually have decreased serum C3 levels, normal levels of C1 and C4, and high levels of C3NeF (autoantibody), which may indicate the presence of renal involvement.

- Antinuclear antibodies (ANA) and antidouble-stranded deoxyribonucleic acid (DNA) antibodies have reportedly been observed in some patients with acquired partial lipodystrophy.

- A genetic workup should be performed if the familial form of lipodystrophy is suggested.

Laboratory work for associated diseases includes:

- Metabolic disease - fasting glucose, glucose tolerance test, lipid profile, and fasting insulin to characterize the insulin resistance state; free testosterone (in women) to look for polycystic ovary syndrome.

- Autoimmune disease - ANA, antidouble-stranded DNA, rheumatoid factor, thyroid antibodies, C3, and C3NeF.

As a confirmatory test, whole-body MRI usually clearly demonstrates the extent of lipodystrophy. MRI is not recommended on a routine basis.

Screening among family members of people with known FH is cost-effective. Other strategies such as universal screening at the age of 16 were suggested in 2001. The latter approach may however be less cost-effective in the short term. Screening at an age lower than 16 was thought likely to lead to an unacceptably high rate of false positives.

A 2007 meta-analysis found that "the proposed strategy of screening children and parents for familial hypercholesterolaemia could have considerable impact in preventing the medical consequences of this disorder in two generations simultaneously." "The use of total cholesterol alone may best discriminate between people with and without FH between the ages of 1 to 9 years."

Screening of toddlers has been suggested, and results of a trial on 10,000 one-year-olds were published in 2016. Work was needed to find whether screening was cost-effective, and acceptable to families.

A review published in 2004, which was based on 35 patients seen by the respective authors over 8 years and also a literature review of 220 cases of acquired partial lipodystrophy (APL), proposed an essential diagnostic criterion. Based on the review and the authors experience, they proposed that APL presents as a gradual onset of bilaterally symmetrical loss of subcutaneous fat from the face, neck, upper extremities, thorax, and abdomen, in the "cephalocaudal" sequence, sparing the lower extremities. The median age of the onset of lipodystrophy was seven years. Several autoimmune diseases, in particular systemic lupus erythematosus and dermatomyositis, were associated with APL. The prevalence rates of diabetes mellitus and impaired glucose tolerance were 6.7% and 8.9%, respectively. Around 83% of APL patients had low complement 3 (C3) levels and the presence of polyclonal immunoglobulin C3 nephritic factor. About 22% of patients developed membranoproliferative glomerulonephritis (MPGN) after a median of about 8 years following the onset of lipodystrophy. Compared with patients without renal disease, those with MPGN had earlier age of onset of lipodystrophy (12.6 ± 10.3 yr vs 7.7 ± 4.4 yr, respectively; p < 0.001) and a higher prevalence of C3 hypocomplementemia (78% vs 95%, respectively; p = 0.02).

The adipose stores of the gluteal regions and lower extremities (including soles) tend to be either preserved or increased, particularly among women. Variable fat loss of the palms, but no loss of intramarrow or retro-orbital fat, has been demonstrated.

Diagnosis is made comprehensively, together with visual observation, body fat assessment, a review of lab panels consisting of A1c, glucose, lipid, and patient history.

Caliper measurements of skinfold thickness is recommended to quantify fat loss as a supportive information. In this measurement, skinfold thickness of less than 10mm for men and 22mm for women at the anterior thigh is suggestive cutoff for the diagnosis of lipodystrophy. Less commonly, biphotonic absorptiometry and magnetic resonance imaging (MRI) can be done for the measurement of body fat.

Other forms of insulin resistance may be assessed for differential diagnosis. Resistance to conventional therapy for hyperglycemia and hypertriglyceridemia serves as an indication for lipodystrophy. Specifically, the diagnosis is strongly considered for those requiring ≥200 units/day of insulin and persistent elevation of ≥250 mg/dl of triglyceride levels.

The use of leptin levels should be carefully approached. While low leptin levels are helpful for making the diagnosis, they are not specific for the lipodystrophy. High leptin levels can help excluding the possible lipodystrophy, but there is no well-established standardized leptin ranges.

CGL patients have to maintain a strict diet for life, as their excess appetite will cause them to overeat. Carbohydrate intake should be restricted in these patients. To avoid chylomicronemia, CGL patients with hypertriglyceridemia need to have a diet very low in fat. CGL patients also need to avoid total proteins, trans fats, and eat high amounts of soluble fiber to avoid getting high levels of cholesterol in the blood.

This condition can be diagnosed by genetic testing. Furthermore, an echocardiogram and X-ray may help in the diagnosis.

This not known with certainty but is estimated to be about one per million. It appears to be more common in females than males.

The differential diagnosis of this condition consists of:

- Hypertrophic cardiomyopathy

- Beckwith-Wiedemann syndrome

- Berardinelli-Seip congenital lipodystrophy

Familial dysautonomia is inherited in an autosomal recessive pattern, which means 2 copies of the gene in each cell are altered. If both parents are shown to be carriers by genetic testing, there is a 25% chance that the child will produce FD. Prenatal diagnosis for pregnancies at increased risk for FD by amniocentesis (for 14–17 weeks) or chorionic villus sampling (for 10–11 weeks) is possible.

Many people with MDP syndrome are high achievers intellectually following careers in law, medicine and computing. A crucial point is that they do not have progeria and there is no evidence of accelerated intellectual decline with age in these patients. Equally life expectancy has not been shown to be reduced. Patients of 65 have been described in the literature and none of the patients are known to have malignancy. Therefore, there are many crucial differences with progeria and the name of progeroid in the title is confusing as this really refers to the lack of fat in the face and taut skin and not any intellectual or other age associated features.

Reversion of lipodystrophy does not occur after withdrawal of protease inhibitors.

In 1993, Peter James Dyck divided HSAN I further into five subtypes HSAN IA-E based on the presence of additional features. These features were thought to result from the genetic diversity of HSAN I (i.e. the expression of different genes, different alleles of a single gene, or modifying genes) or environmental factors. Molecular genetic studies later confirmed the genetic diversity of the disease.

Initial and general approach for AGL patients are to treat the metabolic complications such as leptin-replacement therapy and/or to control the abnormal levels of lipids or glucose levels. Anti-diabetic medications such as insulin, metformin, or thiazolidinediones are used for insulin-resistance or high glucose levels, or statins or fibrates are used for hyperlipidemia. If symptoms persist, metreleptin can be prescribed.

Metreleptin (MYALEPT) is a recombinant human leptin analog and was approved by FDA in 2014 for generalized lipodystrophy as an adjunct therapy to diet to treat the complication of leptin deficiency. It is the only drug option approved for generalized lipodystrophy-related symptoms and is not intended to use for patients with HIV-related lipodystrophy or complications of partial lipodystrophy. Although it is a recombinant human leptin analog, it is not completely the same as natural leptin as it is produced in "e. coli" and has added methionine residues at is amino terminus. It works by binding to the human leptin receptor, ObR, and activates the receptor. The receptor belongs to the Class I cytokine family and signals the JAK/STAT pathway. It is available as 11.3 mg powder in a vial for subcutaneous injection upon reconstitution and needs to be protected from the light. For treatment, patients and their doctors need to be enrolled and certified in the Myalept Risk Evaluation and Mitigation Strategy (REMS) Program because people on this treatment has a risk of developing anti-metreleptin antibodies that decrease the effectiveness of metreleptin, and increased risk of lymphoma. Clinical study with GL patients who took metreleptin had increased insulin sensitivity, as indicated by decreased HbA1c and fasting glucose level, and reduced caloric intake as well as fasting triglyceride levels.

Plasmapheresis was previously an option for lowering extremely high triglyceride levels for preventing pancreatitis and painful xanthoma, but its use has been decreased after the approval of metreleptin.

Cosmetic treatments, such as facial reconstruction or implants, can be done to replace adipose tissues.

Lifestyle modifications are also recommended, including changes into less fat diet and exercise.

The prognosis of the disease is unknown as of December, 2017.

Definitive diagnosis requires LCAT gene analysis for mutation and functional activity. However, numerous lab tests may help with making a diagnosis such as complete blood count (CBC), urinalysis, blood chemistries, lipid panels, and plasma LCAT activity.

Fish-eye disease is characterized by abnormalities like visual impairment, plaques of fatty material, and dense opacification.

GHRH analogs such as tesamorelin can be used to treat HIV-associated lipodystrophy.

As fat cannot be stored under the skin it is important to have a healthy diet without excess fat. Often due to failure to thrive or lack of subcutaneous fat there may have been encouragement to add supplements or fat to the diet however this will not result in any increase in fat under the skin and can easily result in it going into tissues such as the liver or kidney where it is not desired. In people with moderate / severe lipodystrophy a low fat diet would be recommended but in those where the lipodystrophy has not progressed (for example in younger children) a healthy relatively low fat diet may be sufficient. The fat and muscle reduction is not the result of dietary insufficiency and cannot be treated with dietary measures. Apart from diet the other thing that is important is exercise which should be encouraged and will make insulin work more effectively.

In those who have not developed diabetes it is recommended fasting insulin, triglycerides, glucose and HbA1c should be measured annually to monitor insulin resistance and blood glucose.

In those with diabetes it is suggested using Metformin in doses of at least 2g/day as it decreases insulin resistance and improves insulin sensitivity, following appropriate clinical consultation.

The thin skin means if there is trauma there should be rapid attention to any wounds to avoid infection and help primary healing as there can be problems with skin ulcers.

A lipodystrophy can be a lump or small dent in the skin that forms when a person performs injections repeatedly in the same spot. These types of lipodystrophies are harmless and can be avoided by changing (rotating) the locations of injections. For those with diabetes, using purified insulins may also help.

One of the side-effects of lipodystrophy is the rejection of the injected medication, the slowing down of the absorption of the medication, or trauma that can cause bleeding that, in turn, will reject the medication. In any of these scenarios, the dosage of the medication, such as insulin for diabetics, becomes impossible to gauge correctly and the treatment of the disease for which the medication is administered is impaired, thereby allowing the medical condition to worsen.

In some cases, rotation of the injection sites may not be enough to prevent lipodystrophy.

Genetic testing is performed on a small sample of blood from the tested individual. The DNA is examined with a designed probe specific to the known mutations. The accuracy of the test is above 99%. Dr. Anat Blumenfeld of the Hadasah Medical center in Jerusalem identified chromosome number 9 as the responsible chromosome.

The diagnosis of HSAN I is based on the observation of symptoms described above and is supported by a family history suggesting autosomal dominant inheritance. The diagnosis is also supported by additional tests, such as nerve conduction studies in the lower limbs to confirm a sensory and motor neuropathy. In sporadic cases, acquired neuropathies, such as the diabetic foot syndrome and alcoholic neuropathy, can be excluded by the use of magnetic resonance imaging and by interdisciplinary discussion between neurologists, dermatologists, and orthopedics.

The diagnosis of the disease has been revolutionized by the identification of the causative genes. The diagnosis is now based on the detection of the mutations by direct sequencing of the genes. Nevertheless, the accurate phenotyping of patients remains crucial in the diagnosis. For pregnant patients, termination of pregnancy is not recommended.

HSAN I must be distinguished from hereditary motor and sensory neuropathy (HMSN) and other types of hereditary sensory and autonomic neuropathies (HSAN II-V). The prominent sensory abnormalities and foot ulcerations are the only signs to separate HSAN I from HMSN. HSAN II can be differentiated from HSAN I as it is inherited as an autosomal recessive trait, it has earlier disease onset, the sensory loss is diffused to the whole body, and it has less or no motor symptoms. HSAN III-V can be easily distinguished from HSAN I because of congenital disease onset. Moreover, these types exhibit typical features, such as the predominant autonomic disturbances in HSAN III or congenital loss of pain and anhidrosis in HSAN IV.

Diagnosis of acquired dysfibrinogenemia uses the same laboratory tests that are used for congenital dysfibrinogenemia plus evidence for an underlying causative disease.

Lipodystrophy can be caused by metabolic abnormalities due to genetic issues. These are often characterized by insulin resistance and are associated with metabolic syndrome.

Familial partial lipodystrophy (FPL), also known as Köbberling–Dunnigan syndrome, is a rare genetic metabolic condition characterized by the loss of subcutaneous fat.

FPL also refers to a rare metabolic condition in which there is a loss of subcutaneous fat in the arms, legs and lower torso. The upper section of the body, face, neck, shoulders, back and trunk carry an excess amount of fat.

As the body is unable to store fat correctly this leads to fat around all the vital organs and in the blood (triglycerides). This results in heart problems, cirrhosis of the liver, lipoatrophic diabetes, and pancreatitis, along with various other complications.

Approximately 85% of individuals with this disorder have not been diagnosed and consequently are not receiving lipid-lowering treatments. Physical examination findings can help a physician make the diagnosis of FH. Tendon xanthomas are seen in 20-40% of individuals with FH and are pathognomonic for the condition. A xanthelasma or corneal arcus may also be seen. These common signs are supportive of the diagnosis, but are non-specific findings.

Renal failure is the major cause of morbidity and mortality in complete LCAT deficiency, while in partial deficiency (fish eye disease) major cause of morbidity is visual impairment due to corneal opacity. These patients have low HDL cholesterol but surprisingly premature atherosclerosis is not seen. However, there are some reported cases.