Types of Diabetes Explained: Type 1, Type 2, Prediabetes and Gestational Diabetes

Type 1, type 2, prediabetes and gestational diabetes explained: causes, who gets them, how they're diagnosed and what treatment usually involves.

Diabetes is not one condition. The type you have decides how it is treated — whether insulin is needed from day one, whether remission is possible, and which checks matter most. This guide explains the main types in plain language, then describes the four situations doctors see most often.

Four kinds of diabetes · which one describes you?

Diabetes is a group of metabolic disorders characterised by chronic high blood glucose (hyperglycemia). Left unmanaged, it damages small vessels (retina, kidney, nerves) and large vessels (heart, brain, legs). Recognising which type you have — and how recently you were diagnosed — directly shapes what treatment path fits: intensive lifestyle for remission, medication optimisation, insulin support, or bariatric evaluation.

Type 2 Diabetes (T2DM)

~90% of all diabetes globally. The body becomes resistant to insulin AND, over time, produces less. Typically develops in adults 40+, though increasingly in younger South Asians due to genetic susceptibility. Highly reversible in the first 6 years — DiRECT trial (2018) showed 46% remission at 1 year, 36% at 2 years, with intensive weight-loss protocols. First-line meds: metformin, then SGLT2i or GLP-1RA based on comorbidities.

• ~90% of all diabetes cases

• India: 74M+ people, 2nd highest globally

• DiRECT-style remission possible if diagnosed <6 yrs ago

• Metformin → SGLT2i / GLP-1RA / insulin as needed

Type 1 Diabetes (T1DM)

Autoimmune destruction of pancreatic beta cells. Usually diagnosed in children, adolescents or young adults but can present at any age (LADA = Latent Autoimmune Diabetes in Adults). Requires lifelong insulin from diagnosis. Modern care combines CGM with insulin pumps or multiple daily injections (MDI). Time-in-Range >70% is the modern target alongside HbA1c.

• ~5-10% of all diabetes

• Requires lifelong insulin

• CGM + pump technology has transformed outcomes

• Not currently reversible (research ongoing)

Prediabetes

HbA1c 5.7-6.4%, fasting glucose 100-125 mg/dL, or 2-hour OGTT 140-199. Highly reversible — the landmark Diabetes Prevention Program (DPP, NEJM 2002) showed 58% reduction in progression to T2DM with 7% weight loss + 150 min/week activity. Metformin also effective (31% reduction). Indian data (IDPP-1, Ramachandran 2006) confirmed benefit at tighter Asian BMI thresholds. Often silent — screening is essential.

• ~136M adults in India have prediabetes (ICMR-INDIAB)

• Lifestyle → 58% reduced progression (DPP)

• Metformin option → 31% reduction

• Screening from age 30 (Indian guidelines)

Gestational Diabetes (GDM)

Diabetes first detected in pregnancy. Usually 24-28 weeks gestation, screened by OGTT (75g in India per DIPSI/IADPSG criteria). Managed with medical nutrition therapy first, then insulin if needed (metformin acceptable per Indian guidelines but MNT-first). Usually resolves after delivery BUT ~50% develop T2DM within 10 years — long-term follow-up matters.

• 7-14% of Indian pregnancies

• OGTT screening 24-28 weeks (IADPSG/DIPSI)

• MNT-first, insulin if targets missed

• ~50% develop T2DM within 10 years — screen annually

The 4 diabetes profiles we see most often.

Diabetes shows up differently depending on type, how long you've had it, what medications you're on, and what complications have developed. Tap a tab to see what each profile typically looks like, what tests matter, and what care path tends to work best.

Newly Diagnosed T2DM · The remission window (first 6 years)

What it looks like

• Diagnosed T2DM within the last 6 years

• HbA1c often 7-10% at diagnosis (sometimes higher)

• Often overweight or obese (BMI ≥25 in Asians, ≥27 elsewhere)

• On metformin monotherapy or metformin + one other agent

• Beta-cell function still preserved (higher fasting C-peptide)

• Family history often positive

• Frequently sedentary lifestyle, weight gain in last 5-10 years

• May have prediabetes or GDM history

What usually helps

• DiRECT-style intensive weight loss — 12-week structured programme, target ≥10 kg loss

• Very-low-calorie diet (VLCD) option for motivated patients — 800-850 kcal for 8-12 weeks then reintroduction

• GLP-1 RA (semaglutide, tirzepatide) — pharmacological support for weight loss + glycemic control

• CGM setup during and after the intensive phase — watch your remission happen in real time

• Metformin usually continued at low dose during weight loss, may be stopped if remission achieved

• Weekly panel review for the first 12 weeks — dietitian, diabetes educator, diabetologist coordinated

• Realistic expectations: 46% achieve full remission at 1 year (DiRECT); many more achieve near-remission (HbA1c 6.5-7% on minimal meds)

Established T2DM · Focus shifts to organ protection

What it looks like

• T2DM 6+ years, sometimes 15-20+ years

• Multiple medications: often metformin + sulfonylurea/DPP-4i + basal insulin

• Beta-cell function declining (progressive nature of T2DM)

• Some complications may have started: retinopathy, microalbuminuria, peripheral neuropathy, ASCVD

• May have comorbid hypertension, dyslipidemia, CKD, heart failure

• HbA1c may be trending up despite treatment intensification

• Hypoglycemia events becoming more frequent (especially on insulin/sulfonylureas)

• Weight often difficult to lose despite efforts

What usually helps

• Medication rationalisation: replace sulfonylureas (hypoglycemia risk) with SGLT2i or GLP-1RA

• SGLT2i (empagliflozin, dapagliflozin) if any heart failure, CKD, or high CV risk — proven mortality benefit

• GLP-1 RA (semaglutide, tirzepatide) if BMI ≥27 or ASCVD — weight loss + CV protection

• CGM setup to identify hypoglycemia patterns and post-meal spikes

• Aggressive comorbidity management: statin (LDL <70 if ASCVD), ACEi/ARB (if HTN or albuminuria), aspirin (secondary prevention only)

• Annual complications screening: retinography, urine ACR, foot exam, kidney panel, ECG

• Realistic remission possible but less likely — focus is on stable control, quality of life, complication prevention

Type 1 Diabetes · Insulin, CGM, and modern tech

What it looks like

• Usually diagnosed in childhood, adolescence, or young adulthood (but LADA can present at any age)

• Requires exogenous insulin from diagnosis — no exceptions

• Multiple daily injections (MDI) OR insulin pump therapy

• Regular hypoglycemia events without careful management

• Post-meal glucose excursions can be extreme without carb counting

• Exercise, illness, alcohol, menstrual cycle all affect insulin needs

• DKA risk during illness or insulin omission

• Coeliac disease, thyroid disease commonly comorbid

What usually helps

• CGM setup: CGM or CGM — dramatically improves control and reduces hypoglycemia

• Structured basal-bolus regimen: long-acting analog (glargine, degludec) + rapid-acting mealtime (aspart, lispro)

• Insulin pump discussion for those with variable schedules or frequent hypoglycemia

• Carb counting education (DAFNE-style) — foundational skill for flexible insulin dosing

• Hybrid closed-loop systems increasingly available in India — automate basal adjustment

• Annual coeliac screening (TTG-IgA), thyroid screening (TSH), lipid panel

• Adjunctive therapies: SGLT2i can be used off-label with careful DKA monitoring (some countries approved)

• Time-in-Range >70% target (glucose 70-180 mg/dL), less than 4% time hypoglycemic

Prediabetes & Gestational Diabetes · Prevention and reversal windows

What it looks like

• HbA1c 5.7-6.4% (prediabetes) OR pregnancy diagnosis of GDM (24-28 weeks)

• Often no symptoms — detected on routine screening or during pregnancy

• Family history of T2DM very common

• Sedentary lifestyle, weight gain in recent years

• May have PCOS (women), metabolic syndrome features

• For GDM: history of macrosomia, GDM in prior pregnancy, high-risk ethnicity

• Often surprising and confusing diagnosis — "I don't feel diabetic"

• Highly motivated to act

What usually helps

• Prediabetes: DPP protocol — 7% weight loss + 150 min/week moderate activity = 58% risk reduction (NEJM 2002)

• Metformin for high-risk prediabetes (BMI ≥35, age <60, prior GDM) — 31% risk reduction

• GDM: Medical nutrition therapy first (dietitian-led), self-monitored blood glucose 4-7×/day

• GDM insulin if targets not met on MNT alone (fasting >95, 1-hr >140, 2-hr >120 mg/dL)

• GDM metformin acceptable per Indian guidelines but insulin remains first-line if MNT insufficient

• Postpartum: OGTT at 6-12 weeks post-delivery, then annual screening — ~50% develop T2DM within 10 years

• Realistic expectations: 58% of prediabetes can prevent progression; ~90% of GDM resolves post-delivery but recurrence in future pregnancies is common

Recognise your presentation?